Identifying issues and resolutions

Is the system up?

If you have a report that Swift is down, perform the following basic checks:

1. Run swift functional tests.

2. From a server in your data center, use curl to check /healthcheck (see below).

3. If you have a monitoring system, check your monitoring system.

4. Check your hardware load balancers infrastructure.

5. Run swift-recon on a proxy node.

Functional tests usage

We would recommend that you set up the functional tests to run against your production system. Run regularly this can be a useful tool to validate that the system is configured correctly. In addition, it can provide early warning about failures in your system (if the functional tests stop working, user applications will also probably stop working).

A script for running the function tests is located in swift/.functests.

External monitoring

We use pingdom.com to monitor the external Swift API. We suggest the following:

• Do a GET on /healthcheck

• Create a container, make it public (x-container-read: .r*,.rlistings), create a small file in the container; do a GET on the object

Diagnose: General approach

• Look at service status in your monitoring system.

• In addition to system monitoring tools and issue logging by users, swift errors will often result in log entries (see Diagnose: Interpreting messages in /var/log/swift/ files).

• Look at any logs your deployment tool produces.

• Log files should be reviewed for error signatures (see below) that may point to a known issue, or root cause issues reported by the diagnostics tools, prior to escalation.

Dependencies

The Swift software is dependent on overall system health. Operating system level issues with network connectivity, domain name resolution, user management, hardware and system configuration and capacity in terms of memory and free disk space, may result is secondary Swift issues. System level issues should be resolved prior to diagnosis of swift issues.

Diagnose: Swift-dispersion-report

The swift-dispersion-report is a useful tool to gauge the general health of the system. Configure the swift-dispersion report to cover at a minimum every disk drive in your system (usually 1% coverage). See Dispersion Report for details of how to configure and use the dispersion reporting tool.

The swift-dispersion-report tool can take a long time to run, especially if any servers are down. We suggest you run it regularly (e.g., in a cron job) and save the results. This makes it easy to refer to the last report without having to wait for a long-running command to complete.

Diagnose: Is system responding to /healthcheck?

When you want to establish if a swift endpoint is running, run curl -k against https://[ENDPOINT]/healthcheck.

Diagnose: Interpreting messages in /var/log/swift/ files

Note

In the Hewlett Packard Enterprise Helion Public Cloud we send logs to proxy.log (proxy-server logs), server.log (object-server, account-server, container-server logs), background.log (all other servers [object-replicator, etc]).

The following table lists known issues:

Logfile	Signature	Issue	Steps to take
/var/log/syslog	kernel: [] sd …. [csbu:sd…] Sense Key: Medium Error	Suggests disk surface issues	Run swift-drive-audit on the target node to check for disk errors, repair disk errors
/var/log/syslog	kernel: [] sd …. [csbu:sd…] Sense Key: Hardware Error	Suggests storage hardware issues	Run diagnostics on the target node to check for disk failures, replace failed disks
/var/log/syslog	kernel: [] …. I/O error, dev sd…. ,sector ….		Run diagnostics on the target node to check for disk errors
/var/log/syslog	pound: NULL get_thr_arg	Multiple threads woke up	Noise, safe to ignore
/var/log/swift/proxy.log	…. ERROR …. ConnectionTimeout ….	A storage node is not responding in a timely fashion	Check if node is down, not running Swift, unconfigured, storage off-line or for network issues between the proxy and non responding node
/var/log/swift/proxy.log	proxy-server …. HTTP/1.0 500 ….	A proxy server has reported an internal server error	Examine the logs for any errors at the time the error was reported to attempt to understand the cause of the error.
/var/log/swift/server.log	…. ERROR …. ConnectionTimeout ….	A storage server is not responding in a timely fashion	Check if node is down, not running Swift, unconfigured, storage off-line or for network issues between the server and non responding node
/var/log/swift/server.log	…. ERROR …. Remote I/O error: ‘/srv/node/disk….	A storage device is not responding as expected	Run swift-drive-audit and check the filesystem named in the error for corruption (unmount & xfs_repair). Check if the filesystem is mounted and working.
/var/log/swift/background.log	object-server ERROR container update failed …. Connection refused	A container server node could not be contacted	Check if node is down, not running Swift, unconfigured, storage off-line or for network issues between the server and non responding node
/var/log/swift/background.log	object-updater ERROR with remote …. ConnectionTimeout	The remote container server is busy	If the container is very large, some errors updating it can be expected. However, this error can also occur if there is a networking issue.
/var/log/swift/background.log	account-reaper STDOUT: …. error: ECONNREFUSED	Network connectivity issue or the target server is down.	Resolve network issue or reboot the target server
/var/log/swift/background.log	…. ERROR …. ConnectionTimeout	A storage server is not responding in a timely fashion	The target server may be busy. However, this error can also occur if there is a networking issue.
/var/log/swift/background.log	…. ERROR syncing …. Timeout	A timeout occurred syncing data to another node.	The target server may be busy. However, this error can also occur if there is a networking issue.
/var/log/swift/background.log	…. ERROR Remote drive not mounted ….	A storage server disk is unavailable	Repair and remount the file system (on the remote node)
/var/log/swift/background.log	object-replicator …. responded as unmounted	A storage server disk is unavailable	Repair and remount the file system (on the remote node)
/var/log/swift/*.log	STDOUT: EXCEPTION IN	A unexpected error occurred	Read the Traceback details, if it matches known issues (e.g. active network/disk issues), check for re-ocurrences after the primary issues have been resolved
/var/log/rsyncd.log	rsync: mkdir “/disk….failed: No such file or directory….	A local storage server disk is unavailable	Run diagnostics on the node to check for a failed or unmounted disk
/var/log/swift*	Exception: Could not bind to 0.0.0.0:6xxx	Possible Swift process restart issue. This indicates an old swift process is still running.	Restart Swift services. If some swift services are reported down, check if they left residual process behind.

Diagnose: Parted reports the backup GPT table is corrupt

• If a GPT table is broken, a message like the following should be observed when the following command is run:

  $ sudo parted -l
  

  Error: The backup GPT table is corrupt, but the primary appears OK,
  so that will be used.
  
  OK/Cancel?
  

To fix, go to Fix broken GPT table (broken disk partition)

Diagnose: Drives diagnostic reports a FS label is not acceptable

If diagnostics reports something like “FS label: obj001dsk011 is not acceptable”, it indicates that a partition has a valid disk label, but an invalid filesystem label. In such cases proceed as follows:

1. Verify that the disk labels are correct:

   FS=/dev/sd#1
   
   sudo parted -l | grep object
   

2. If partition labels are inconsistent then, resolve the disk label issues before proceeding:

   sudo parted -s ${FS} name ${PART_NO} ${PART_NAME} #Partition Label
   #PART_NO is 1 for object disks and 3 for OS disks
   #PART_NAME follows the convention seen in "sudo parted -l | grep object"
   

3. If the Filesystem label is missing then create it with care:

   sudo xfs_admin -l ${FS} #Filesystem label (12 Char limit)
   
   #Check for the existence of a FS label
   
   OBJNO=<3 Length Object No.>
   
   #I.E OBJNO for sw-stbaz3-object0007 would be 007
   
   DISKNO=<3 Length Disk No.>
   
   #I.E DISKNO for /dev/sdb would be 001, /dev/sdc would be 002 etc.
   
   sudo xfs_admin -L "obj${OBJNO}dsk${DISKNO}" ${FS}
   
   #Create a FS Label
   

Diagnose: Failed LUNs

Note

The HPE Helion Public Cloud uses direct attach SmartArray controllers/drives. The information here is specific to that environment. The hpacucli utility mentioned here may be called hpssacli in your environment.

The swift_diagnostics mount checks may return a warning that a LUN has failed, typically accompanied by DriveAudit check failures and device errors.

Such cases are typically caused by a drive failure, and if drive check also reports a failed status for the underlying drive, then follow the procedure to replace the disk.

Otherwise the lun can be re-enabled as follows:

1. Generate a hpssacli diagnostic report. This report allows the DC team to troubleshoot potential cabling or hardware issues so it is imperative that you run it immediately when troubleshooting a failed LUN. You will come back later and grep this file for more details, but just generate it for now.

   sudo hpssacli controller all diag file=/tmp/hpacu.diag ris=on xml=off zip=off
   

Export the following variables using the below instructions before proceeding further.

1. Print a list of logical drives and their numbers and take note of the failed drive’s number and array value (example output: “array A logicaldrive 1…” would be exported as LDRIVE=1):

   sudo hpssacli controller slot=1 ld all show
   

2. Export the number of the logical drive that was retrieved from the previous command into the LDRIVE variable:

   export LDRIVE=<LogicalDriveNumber>
   

3. Print the array value and Port:Box:Bay for all drives and take note of the Port:Box:Bay for the failed drive (example output: ” array A physicaldrive 2C:1:1…” would be exported as PBOX=2C:1:1). Match the array value of this output with the array value obtained from the previous command to be sure you are working on the same drive. Also, the array value usually matches the device name (For example, /dev/sdc in the case of “array c”), but we will run a different command to be sure we are operating on the correct device.

   sudo hpssacli controller slot=1 pd all show
   

Note

Sometimes a LUN may appear to be failed as it is not and cannot be mounted but the hpssacli/parted commands may show no problems with the LUNS/drives. In this case, the filesystem may be corrupt and may be necessary to run sudo xfs_check /dev/sd[a-l][1-2] to see if there is an xfs issue. The results of running this command may require that xfs_repair is run.

1. Export the Port:Box:Bay for the failed drive into the PBOX variable:

   export PBOX=<Port:Box:Bay>
   

2. Print the physical device information and take note of the Disk Name (example output: “Disk Name: /dev/sdk” would be exported as DEV=/dev/sdk):

   sudo hpssacli controller slot=1 ld ${LDRIVE} show detail | grep -i "Disk Name"
   

3. Export the device name variable from the preceding command (example: /dev/sdk):

   export DEV=<Device>
   

4. Export the filesystem variable. Disks that are split between the operating system and data storage, typically sda and sdb, should only have repairs done on their data filesystem, usually /dev/sda2 and /dev/sdb2, Other data only disks have just one partition on the device, so the filesystem will be 1. In any case you should verify the data filesystem by running df -h | grep /srv/node and using the listed data filesystem for the device in question as the export. For example: /dev/sdk1.

   export FS=<Filesystem>
   

5. Verify the LUN is failed, and the device is not:

   sudo hpssacli controller slot=1 ld all show
   sudo hpssacli controller slot=1 pd all show
   sudo hpssacli controller slot=1 ld ${LDRIVE} show detail
   sudo hpssacli controller slot=1 pd ${PBOX} show detail
   

6. Stop the swift and rsync service:

   sudo service rsync stop
   sudo swift-init shutdown all
   

7. Unmount the problem drive, fix the LUN and the filesystem:

   sudo umount ${FS}
   

8. If umount fails, you should run lsof search for the mountpoint and kill any lingering processes before repeating the unpount:

   sudo hpacucli controller slot=1 ld ${LDRIVE} modify reenable
   sudo xfs_repair ${FS}
   

9. If the xfs_repair complains about possible journal data, use the xfs_repair -L option to zeroise the journal log.

10. Once complete test-mount the filesystem, and tidy up its lost and found area.

    sudo mount ${FS} /mnt
    sudo rm -rf /mnt/lost+found/
    sudo umount /mnt
    

11. Mount the filesystem and restart swift and rsync.

12. Run the following to determine if a DC ticket is needed to check the cables on the node:

    grep -y media.exchanged /tmp/hpacu.diag
    grep -y hot.plug.count /tmp/hpacu.diag
    

13. If the output reports any non 0x00 values, it suggests that the cables should be checked. For example, log a DC ticket to check the sas cables between the drive and the expander.

Diagnose: Slow disk devices

Note

collectl is an open-source performance gathering/analysis tool.

If the diagnostics report a message such as sda: drive is slow, you should log onto the node and run the following command (remove -c 1 option to continuously monitor the data):

$ /usr/bin/collectl -s D -c 1
waiting for 1 second sample...
# DISK STATISTICS (/sec)
#          <---------reads---------><---------writes---------><--------averages--------> Pct
#Name       KBytes Merged  IOs Size  KBytes Merged  IOs Size  RWSize  QLen  Wait SvcTim Util
sdb            204      0   33    6      43      0    4   11       6     1     7      6   23
sda             84      0   13    6     108     21    6   18      10     1     7      7   13
sdc            100      0   16    6       0      0    0    0       6     1     7      6    9
sdd            140      0   22    6      22      0    2   11       6     1     9      9   22
sde             76      0   12    6     255      0   52    5       5     1     2      1   10
sdf            276      0   44    6       0      0    0    0       6     1    11      8   38
sdg            112      0   17    7      18      0    2    9       6     1     7      7   13
sdh           3552      0   73   49       0      0    0    0      48     1     9      8   62
sdi             72      0   12    6       0      0    0    0       6     1     8      8   10
sdj            112      0   17    7      22      0    2   11       7     1    10      9   18
sdk            120      0   19    6      21      0    2   11       6     1     8      8   16
sdl            144      0   22    7      18      0    2    9       6     1     9      7   18
dm-0             0      0    0    0       0      0    0    0       0     0     0      0    0
dm-1             0      0    0    0      60      0   15    4       4     0     0      0    0
dm-2             0      0    0    0      48      0   12    4       4     0     0      0    0
dm-3             0      0    0    0       0      0    0    0       0     0     0      0    0
dm-4             0      0    0    0       0      0    0    0       0     0     0      0    0
dm-5             0      0    0    0       0      0    0    0       0     0     0      0    0

Look at the Wait and SvcTime values. It is not normal for these values to exceed 50msec. This is known to impact customer performance (upload/download). For a controller problem, many/all drives will show long wait and service times. A reboot may correct the problem; otherwise hardware replacement is needed.

Another way to look at the data is as follows:

$ /opt/hp/syseng/disk-anal.pl -d
Disk: sda  Wait: 54580 371  65  25  12   6   6   0   1   2   0  46
Disk: sdb  Wait: 54532 374  96  36  16   7   4   1   0   2   0  46
Disk: sdc  Wait: 54345 554 105  29  15   4   7   1   4   4   0  46
Disk: sdd  Wait: 54175 553 254  31  20  11   6   6   2   2   1  53
Disk: sde  Wait: 54923  66  56  15   8   7   7   0   1   0   2  29
Disk: sdf  Wait: 50952 941 565 403 426 366 442 447 338  99  38  97
Disk: sdg  Wait: 50711 689 808 562 642 675 696 185  43  14   7  82
Disk: sdh  Wait: 51018 668 688 483 575 542 692 275  55  22   9  87
Disk: sdi  Wait: 51012 1011 849 672 568 240 344 280  38  13   6  81
Disk: sdj  Wait: 50724 743 770 586 662 509 684 283  46  17  11  79
Disk: sdk  Wait: 50886 700 585 517 633 511 729 352  89  23   8  81
Disk: sdl  Wait: 50106 617 794 553 604 504 532 501 288 234 165 216
Disk: sda  Time: 55040  22  16   6   1   1  13   0   0   0   3  12

Disk: sdb  Time: 55014  41  19   8   3   1   8   0   0   0   3  17
Disk: sdc  Time: 55032  23  14   8   9   2   6   1   0   0   0  19
Disk: sdd  Time: 55022  29  17  12   6   2  11   0   0   0   1  14
Disk: sde  Time: 55018  34  15  11  12   1   9   0   0   0   2  12
Disk: sdf  Time: 54809 250  45   7   1   0   0   0   0   0   1   1
Disk: sdg  Time: 55070  36   6   2   0   0   0   0   0   0   0   0
Disk: sdh  Time: 55079  33   2   0   0   0   0   0   0   0   0   0
Disk: sdi  Time: 55074  28   7   2   0   0   2   0   0   0   0   1
Disk: sdj  Time: 55067  35  10   0   1   0   0   0   0   0   0   1
Disk: sdk  Time: 55068  31  10   3   0   0   1   0   0   0   0   1
Disk: sdl  Time: 54905 130  61   7   3   4   1   0   0   0   0   3

This shows the historical distribution of the wait and service times over a day. This is how you read it:

• sda did 54580 operations with a short wait time, 371 operations with a longer wait time and 65 with an even longer wait time.

• sdl did 50106 operations with a short wait time, but as you can see many took longer.

There is a clear pattern that sdf to sdl have a problem. Actually, sda to sde would more normally have lots of zeros in their data. But maybe this is a busy system. In this example it is worth changing the controller as the individual drives may be ok.

After the controller is changed, use collectl -s D as described above to see if the problem has cleared. disk-anal.pl will continue to show historical data. You can look at recent data as follows. It only looks at data from 13:15 to 14:15. As you can see, this is a relatively clean system (few if any long wait or service times):

$ /opt/hp/syseng/disk-anal.pl -d -t 13:15-14:15
Disk: sda  Wait:  3600   0   0   0   0   0   0   0   0   0   0   0
Disk: sdb  Wait:  3600   0   0   0   0   0   0   0   0   0   0   0
Disk: sdc  Wait:  3600   0   0   0   0   0   0   0   0   0   0   0
Disk: sdd  Wait:  3600   0   0   0   0   0   0   0   0   0   0   0
Disk: sde  Wait:  3600   0   0   0   0   0   0   0   0   0   0   0
Disk: sdf  Wait:  3600   0   0   0   0   0   0   0   0   0   0   0
Disk: sdg  Wait:  3594   6   0   0   0   0   0   0   0   0   0   0
Disk: sdh  Wait:  3600   0   0   0   0   0   0   0   0   0   0   0
Disk: sdi  Wait:  3600   0   0   0   0   0   0   0   0   0   0   0
Disk: sdj  Wait:  3600   0   0   0   0   0   0   0   0   0   0   0
Disk: sdk  Wait:  3600   0   0   0   0   0   0   0   0   0   0   0
Disk: sdl  Wait:  3599   1   0   0   0   0   0   0   0   0   0   0
Disk: sda  Time:  3600   0   0   0   0   0   0   0   0   0   0   0
Disk: sdb  Time:  3600   0   0   0   0   0   0   0   0   0   0   0
Disk: sdc  Time:  3600   0   0   0   0   0   0   0   0   0   0   0
Disk: sdd  Time:  3600   0   0   0   0   0   0   0   0   0   0   0
Disk: sde  Time:  3600   0   0   0   0   0   0   0   0   0   0   0
Disk: sdf  Time:  3600   0   0   0   0   0   0   0   0   0   0   0
Disk: sdg  Time:  3594   6   0   0   0   0   0   0   0   0   0   0
Disk: sdh  Time:  3600   0   0   0   0   0   0   0   0   0   0   0
Disk: sdi  Time:  3600   0   0   0   0   0   0   0   0   0   0   0
Disk: sdj  Time:  3600   0   0   0   0   0   0   0   0   0   0   0
Disk: sdk  Time:  3600   0   0   0   0   0   0   0   0   0   0   0
Disk: sdl  Time:  3599   1   0   0   0   0   0   0   0   0   0   0

For long wait times, where the service time appears normal is to check the logical drive cache status. While the cache may be enabled, it can be disabled on a per-drive basis.

Diagnose: Slow network link - Measuring network performance

Network faults can cause performance between Swift nodes to degrade. Testing with netperf is recommended. Other methods (such as copying large files) may also work, but can produce inconclusive results.

Install netperf on all systems if not already installed. Check that the UFW rules for its control port are in place. However, there are no pre-opened ports for netperf’s data connection. Pick a port number. In this example, 12866 is used because it is one higher than netperf’s default control port number, 12865. If you get very strange results including zero values, you may not have gotten the data port opened in UFW at the target or may have gotten the netperf command-line wrong.

Pick a source and target node. The source is often a proxy node and the target is often an object node. Using the same source proxy you can test communication to different object nodes in different AZs to identity possible bottlenecks.

Running tests

1. Prepare the target node as follows:

   sudo iptables -I INPUT -p tcp -j ACCEPT
   

   Or, do:

   sudo ufw allow 12866/tcp
   

2. On the source node, run the following command to check throughput. Note the double-dash before the -P option. The command takes 10 seconds to complete. The target node is 192.168.245.5.

   $ netperf -H 192.168.245.5 -- -P 12866
   MIGRATED TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 12866 AF_INET to
   <redacted>.72.4 (<redacted>.72.4) port 12866 AF_INET : demo
   Recv   Send    Send
   Socket Socket  Message  Elapsed
   Size   Size    Size     Time     Throughput
   bytes  bytes   bytes    secs.    10^6bits/sec
   87380  16384  16384    10.02     923.69
   

3. On the source node, run the following command to check latency:

   $ netperf -H 192.168.245.5 -t TCP_RR -- -P 12866
   MIGRATED TCP REQUEST/RESPONSE TEST from 0.0.0.0 (0.0.0.0) port 12866
   AF_INET to <redacted>.72.4 (<redacted>.72.4) port 12866 AF_INET : demo
   : first burst 0
   Local  Remote Socket   Size    Request  Resp.   Elapsed  Trans.
   Send   Recv   Size     Size    Time     Rate
   bytes  Bytes  bytes    bytes   secs.    per sec
   16384  87380  1        1       10.00    11753.37
   16384  87380
   

Expected results

Faults will show up as differences between different pairs of nodes. However, for reference, here are some expected numbers:

• For throughput, proxy to proxy, expect ~9300 Mbit/sec (proxies have a 10Ge link).

• For throughout, proxy to object, expect ~920 Mbit/sec (at time of writing this, object nodes have a 1Ge link).

• For throughput, object to object, expect ~920 Mbit/sec.

• For latency (all types), expect ~11000 transactions/sec.

Diagnose: Remapping sectors experiencing UREs

1. Find the bad sector, device, and filesystem in kern.log.

2. Set the environment variables SEC, DEV & FS, for example:

   SEC=2930954256
   DEV=/dev/sdi
   FS=/dev/sdi1
   

3. Verify that the sector is bad:

   sudo dd if=${DEV} of=/dev/null bs=512 count=1 skip=${SEC}
   

4. If the sector is bad this command will output an input/output error:

   dd: reading `/dev/sdi`: Input/output error
   0+0 records in
   0+0 records out
   

5. Prevent chef from attempting to re-mount the filesystem while the repair is in progress:

   sudo mv /etc/chef/client.pem /etc/chef/xx-client.xx-pem
   

6. Stop the swift and rsync service:

   sudo service rsync stop
   sudo swift-init shutdown all
   

7. Unmount the problem drive:

   sudo umount ${FS}
   

8. Overwrite/remap the bad sector:

   sudo dd_rescue -d -A -m8b -s ${SEC}b ${DEV} ${DEV}
   

9. This command should report an input/output error the first time it is run. Run the command a second time, if it successfully remapped the bad sector it should not report an input/output error.

10. Verify the sector is now readable:

    sudo dd if=${DEV} of=/dev/null bs=512 count=1 skip=${SEC}
    

11. If the sector is now readable this command should not report an input/output error.

12. If more than one problem sector is listed, set the SEC environment variable to the next sector in the list:

    SEC=123456789
    

13. Repeat from step 8.

14. Repair the filesystem:

    sudo xfs_repair ${FS}
    

15. If xfs_repair reports that the filesystem has valuable filesystem changes:

    sudo xfs_repair ${FS}
    Phase 1 - find and verify superblock...
    Phase 2 - using internal log
            - zero log...
    ERROR: The filesystem has valuable metadata changes in a log which
    needs to be replayed.
    Mount the filesystem to replay the log, and unmount it before
    re-running xfs_repair.
    If you are unable to mount the filesystem, then use the -L option to
    destroy the log and attempt a repair. Note that destroying the log may
    cause corruption -- please attempt a mount of the filesystem before
    doing this.
    

16. You should attempt to mount the filesystem, and clear the lost+found area:

    sudo mount $FS /mnt
    sudo rm -rf /mnt/lost+found/*
    sudo umount /mnt
    

17. If the filesystem fails to mount then you will need to use the xfs_repair -L option to force log zeroing. Repeat step 11.

18. If xfs_repair reports that an additional input/output error has been encountered, get the sector details as follows:

    sudo grep "I/O error" /var/log/kern.log | grep sector | tail -1
    

19. If new input/output error is reported then set the SEC environment variable to the problem sector number:

    SEC=234567890
    

20. Repeat from step 8

21. Remount the filesystem and restart swift and rsync.

    • If all UREs in the kern.log have been fixed and you are still unable to have xfs_repair disk, it is possible that the URE’s have corrupted the filesystem or possibly destroyed the drive altogether. In this case, the first step is to re-format the filesystem and if this fails, get the disk replaced.

Diagnose: High system latency

Note

The latency measurements described here are specific to the HPE Helion Public Cloud.

• A bad NIC on a proxy server. However, as explained above, this usually causes the peak to rise, but average should remain near normal parameters. A quick fix is to shutdown the proxy.

• A stuck memcache server. Accepts connections, but then will not respond. Expect to see timeout messages in /var/log/proxy.log (port 11211). Swift Diags will also report this as a failed node/port. A quick fix is to shutdown the proxy server.

• A bad/broken object server can also cause problems if the accounts used by the monitor program happen to live on the bad object server.

• A general network problem within the data canter. Compare the results with the Pingdom monitors to see if they also have a problem.

Diagnose: Interface reports errors

Should a network interface on a Swift node begin reporting network errors, it may well indicate a cable, switch, or network issue.

Get an overview of the interface with:

sudo ifconfig eth{n}
sudo ethtool eth{n}

The Link Detected: indicator will read yes if the nic is cabled.

Establish the adapter type with:

sudo ethtool  -i eth{n}

Gather the interface statistics with:

sudo ethtool  -S eth{n}

If the nick supports self test, this can be performed with:

sudo ethtool  -t eth{n}

Self tests should read PASS if the nic is operating correctly.

Nic module drivers can be re-initialised by carefully removing and re-installing the modules (this avoids rebooting the server). For example, mellanox drivers use a two part driver mlx4_en and mlx4_core. To reload these you must carefully remove the mlx4_en (ethernet) then the mlx4_core modules, and reinstall them in the reverse order.

As the interface will be disabled while the modules are unloaded, you must be very careful not to lock yourself out so it may be better to script this.

Diagnose: Hung swift object replicator

A replicator reports in its log that remaining time exceeds 100 hours. This may indicate that the swift object-replicator is stuck and not making progress. Another useful way to check this is with the ‘swift-recon -r’ command on a swift proxy server:

sudo swift-recon -r
===============================================================================

--> Starting reconnaissance on 384 hosts
===============================================================================
[2013-07-17 12:56:19] Checking on replication
[replication_time] low: 2, high: 80, avg: 28.8, total: 11037, Failed: 0.0%, no_result: 0, reported: 383
Oldest completion was 2013-06-12 22:46:50 (12 days ago) by 192.168.245.3:6200.
Most recent completion was 2013-07-17 12:56:19 (5 seconds ago) by 192.168.245.5:6200.
===============================================================================

The Oldest completion line in this example indicates that the object-replicator on swift object server 192.168.245.3 has not completed the replication cycle in 12 days. This replicator is stuck. The object replicator cycle is generally less than 1 hour. Though an replicator cycle of 15-20 hours can occur if nodes are added to the system and a new ring has been deployed.

You can further check if the object replicator is stuck by logging on the object server and checking the object replicator progress with the following command:

#  sudo grep object-rep /var/log/swift/background.log | grep -e "Starting object replication" -e "Object replication complete" -e "partitions rep"
Jul 16 06:25:46 192.168.245.4 object-replicator 15344/16450 (93.28%) partitions replicated in 69018.48s (0.22/sec, 22h remaining)
Jul 16 06:30:46 192.168.245.4object-replicator 15344/16450 (93.28%) partitions replicated in 69318.58s (0.22/sec, 22h remaining)
Jul 16 06:35:46 192.168.245.4 object-replicator 15344/16450 (93.28%) partitions replicated in 69618.63s (0.22/sec, 23h remaining)
Jul 16 06:40:46 192.168.245.4 object-replicator 15344/16450 (93.28%) partitions replicated in 69918.73s (0.22/sec, 23h remaining)
Jul 16 06:45:46 192.168.245.4 object-replicator 15348/16450 (93.30%) partitions replicated in 70218.75s (0.22/sec, 24h remaining)
Jul 16 06:50:47 192.168.245.4object-replicator 15348/16450 (93.30%) partitions replicated in 70518.85s (0.22/sec, 24h remaining)
Jul 16 06:55:47 192.168.245.4 object-replicator 15348/16450 (93.30%) partitions replicated in 70818.95s (0.22/sec, 25h remaining)
Jul 16 07:00:47 192.168.245.4 object-replicator 15348/16450 (93.30%) partitions replicated in 71119.05s (0.22/sec, 25h remaining)
Jul 16 07:05:47 192.168.245.4 object-replicator 15348/16450 (93.30%) partitions replicated in 71419.15s (0.21/sec, 26h remaining)
Jul 16 07:10:47 192.168.245.4object-replicator 15348/16450 (93.30%) partitions replicated in 71719.25s (0.21/sec, 26h remaining)
Jul 16 07:15:47 192.168.245.4 object-replicator 15348/16450 (93.30%) partitions replicated in 72019.27s (0.21/sec, 27h remaining)
Jul 16 07:20:47 192.168.245.4object-replicator 15348/16450 (93.30%) partitions replicated in 72319.37s (0.21/sec, 27h remaining)
Jul 16 07:25:47 192.168.245.4 object-replicator 15348/16450 (93.30%) partitions replicated in 72619.47s (0.21/sec, 28h remaining)
Jul 16 07:30:47 192.168.245.4 object-replicator 15348/16450 (93.30%) partitions replicated in 72919.56s (0.21/sec, 28h remaining)
Jul 16 07:35:47 192.168.245.4 object-replicator 15348/16450 (93.30%) partitions replicated in 73219.67s (0.21/sec, 29h remaining)
Jul 16 07:40:47 192.168.245.4 object-replicator 15348/16450 (93.30%) partitions replicated in 73519.76s (0.21/sec, 29h remaining)

The above status is output every 5 minutes to /var/log/swift/background.log.

Note

The ‘remaining’ time is increasing as time goes on, normally the time remaining should be decreasing. Also note the partition number. For example, 15344 remains the same for several status lines. Eventually the object replicator detects the hang and attempts to make progress by killing the problem thread. The replicator then progresses to the next partition but quite often it again gets stuck on the same partition.

One of the reasons for the object replicator hanging like this is filesystem corruption on the drive. The following is a typical log entry of a corrupted filesystem detected by the object replicator:

# sudo bzgrep "Remote I/O error" /var/log/swift/background.log* |grep srv | - tail -1
Jul 12 03:33:30 192.168.245.4 object-replicator STDOUT: ERROR:root:Error hashing suffix#012Traceback (most recent call last):#012 File
"/usr/lib/python2.7/dist-packages/swift/obj/replicator.py", line 199, in get_hashes#012 hashes[suffix] = hash_suffix(suffix_dir,
reclaim_age)#012 File "/usr/lib/python2.7/dist-packages/swift/obj/replicator.py", line 84, in hash_suffix#012 path_contents =
sorted(os.listdir(path))#012OSError: [Errno 121] Remote I/O error: '/srv/node/disk4/objects/1643763/b51'

An ls of the problem file or directory usually shows something like the following:

# ls -l /srv/node/disk4/objects/1643763/b51
ls: cannot access /srv/node/disk4/objects/1643763/b51: Remote I/O error

If no entry with Remote I/O error occurs in the background.log it is not possible to determine why the object-replicator is hung. It may be that the Remote I/O error entry is older than 7 days and so has been rotated out of the logs. In this scenario it may be best to simply restart the object-replicator.

1. Stop the object-replicator:

   # sudo swift-init object-replicator stop
   

2. Make sure the object replicator has stopped, if it has hung, the stop command will not stop the hung process:

   # ps auxww | - grep swift-object-replicator
   

3. If the previous ps shows the object-replicator is still running, kill the process:

   # kill -9 <pid-of-swift-object-replicator>
   

4. Start the object-replicator:

   # sudo swift-init object-replicator start
   

If the above grep did find an Remote I/O error then it may be possible to repair the problem filesystem.

1. Stop swift and rsync:

   # sudo swift-init all shutdown
   # sudo service rsync stop
   

2. Make sure all swift process have stopped:

   # ps auxww | grep swift | grep python
   

3. Kill any swift processes still running.

4. Unmount the problem filesystem:

   # sudo umount /srv/node/disk4
   

5. Repair the filesystem:

   # sudo xfs_repair -P /dev/sde1
   

6. If the xfs_repair fails then it may be necessary to re-format the filesystem. See Procedure: Fix broken XFS filesystem. If the xfs_repair is successful, re-enable chef using the following command and replication should commence again.

Diagnose: High CPU load

The CPU load average on an object server, as shown with the ‘uptime’ command, is typically under 10 when the server is lightly-moderately loaded:

$ uptime
07:59:26 up 99 days,  5:57,  1 user,  load average: 8.59, 8.39, 8.32

During times of increased activity, due to user transactions or object replication, the CPU load average can increase to to around 30.

However, sometimes the CPU load average can increase significantly. The following is an example of an object server that has extremely high CPU load:

$ uptime
07:44:02 up 18:22,  1 user,  load average: 407.12, 406.36, 404.59

Further issues and resolutions

Note

The urgency levels in each Action column indicates whether or not it is required to take immediate action, or if the problem can be worked on during business hours.

Scenario	Description	Action
/healthcheck latency is high.	The /healthcheck test does not tax the proxy very much so any drop in value is probably related to network issues, rather than the proxies being very busy. A very slow proxy might impact the average number, but it would need to be very slow to shift the number that much.	Check networks. Do a curl https://<ip-address>:<port>/healthcheck where ip-address is individual proxy IP address. Repeat this for every proxy server to see if you can pin point the problem. Urgency: If there are other indications that your system is slow, you should treat this as an urgent problem.
Swift process is not running.	You can use swift-init status to check if swift processes are running on any given server.	Run this command: sudo swift-init all start Examine messages in the swift log files to see if there are any error messages related to any of the swift processes since the time you ran the swift-init command. Take any corrective actions that seem necessary. Urgency: If this only affects one server, and you have more than one, identifying and fixing the problem can wait until business hours. If this same problem affects many servers, then you need to take corrective action immediately.
ntpd is not running.	NTP is not running.	Configure and start NTP. Urgency: For proxy servers, this is vital.
Host clock is not syncd to an NTP server.	Node time settings does not match NTP server time. This may take some time to sync after a reboot.	Assuming NTP is configured and running, you have to wait until the times sync.
A swift process has hundreds, to thousands of open file descriptors.	May happen to any of the swift processes. Known to have happened with a rsyslod restart and where /tmp was hanging.	Restart the swift processes on the affected node: % sudo swift-init all reload Urgency: If known performance problem: Immediate If system seems fine: Medium
A swift process is not owned by the swift user.	If the UID of the swift user has changed, then the processes might not be owned by that UID.	Urgency: If this only affects one server, and you have more than one, identifying and fixing the problem can wait until business hours. If this same problem affects many servers, then you need to take corrective action immediately.
Object account or container files not owned by swift.	This typically happens if during a reinstall or a re-image of a server that the UID of the swift user was changed. The data files in the object account and container directories are owned by the original swift UID. As a result, the current swift user does not own these files.	Correct the UID of the swift user to reflect that of the original UID. An alternate action is to change the ownership of every file on all file systems. This alternate action is often impractical and will take considerable time. Urgency: If this only affects one server, and you have more than one, identifying and fixing the problem can wait until business hours. If this same problem affects many servers, then you need to take corrective action immediately.
A disk drive has a high IO wait or service time.	If high wait IO times are seen for a single disk, then the disk drive is the problem. If most/all devices are slow, the controller is probably the source of the problem. The controller cache may also be miss configured – which will cause similar long wait or service times.	As a first step, if your controllers have a cache, check that it is enabled and their battery/capacitor is working. Second, reboot the server. If problem persists, file a DC ticket to have the drive or controller replaced. See Diagnose: Slow disk devices on how to check the drive wait or service times. Urgency: Medium
The network interface is not up.	Use the ifconfig and ethtool commands to determine the network state.	You can try restarting the interface. However, generally the interface (or cable) is probably broken, especially if the interface is flapping. Urgency: If this only affects one server, and you have more than one, identifying and fixing the problem can wait until business hours. If this same problem affects many servers, then you need to take corrective action immediately.
Network interface card (NIC) is not operating at the expected speed.	The NIC is running at a slower speed than its nominal rated speed. For example, it is running at 100 Mb/s and the NIC is a 1Ge NIC.	Try resetting the interface with: sudo ethtool -s eth0 speed 1000 … and then run: sudo lshw -class See if size goes to the expected speed. Failing that, check hardware (NIC cable/switch port). If persistent, consider shutting down the server (especially if a proxy) until the problem is identified and resolved. If you leave this server running it can have a large impact on overall performance. Urgency: High
The interface RX/TX error count is non-zero.	A value of 0 is typical, but counts of 1 or 2 do not indicate a problem.	For low numbers (For example, 1 or 2), you can simply ignore. Numbers in the range 3-30 probably indicate that the error count has crept up slowly over a long time. Consider rebooting the server to remove the report from the noise. Typically, when a cable or interface is bad, the error count goes to 400+. For example, it stands out. There may be other symptoms such as the interface going up and down or not running at correct speed. A server with a high error count should be watched. If the error count continues to climb, consider taking the server down until it can be properly investigated. In any case, a reboot should be done to clear the error count. Urgency: High, if the error count increasing.
In a swift log you see a message that a process has not replicated in over 24 hours.	The replicator has not successfully completed a run in the last 24 hours. This indicates that the replicator has probably hung.	Use swift-init to stop and then restart the replicator process. Urgency: Low. However if you recently added or replaced disk drives then you should treat this urgently.
Container Updater has not run in 4 hour(s).	The service may appear to be running however, it may be hung. Examine their swift logs to see if there are any error messages relating to the container updater. This may potentially explain why the container is not running.	Urgency: Medium This may have been triggered by a recent restart of the rsyslog daemon. Restart the service with: .. code: sudo swift-init <service> reload
Object replicator: Reports the remaining time and that time is more than 100 hours.	Each replication cycle the object replicator writes a log message to its log reporting statistics about the current cycle. This includes an estimate for the remaining time needed to replicate all objects. If this time is longer than 100 hours, there is a problem with the replication process.	Urgency: Medium Restart the service with: .. code: sudo swift-init object-replicator reload Check that the remaining replication time is going down.