Troubleshooting

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Troubleshooting

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NOTE. OPTIMUMCACHE IS NO LONGER SUPPORTED.

 

Installing for FS is different from Ext4

 

For now Ext4 is the only supported file system type. If a host has no Ext4 filesystem mounted, OptimumCache package installation will be abandoned:

 

Preparing packages for installation...

Cannot continue: Ext4 partition is the only supported by OptimiumCache, there is no one in fstab

error: %pre(optimumcache-0.1-22.el6.cloudlinux.x86_64) scriptlet failed, exit status 1

error:   install: %pre scriptlet failed (2), skipping

 

Also, an attempt to add for caching directory, which does not reside on Ext4, will fail:

 

# occtl --mark-dir /home --recursive

mount: / not mounted already, or bad option

optimumcache: Can not mount device. rc[8192]

Error: mark[1]: /usr/bin/optimumcache mark --recursive /home

 

Yum fails to install Perl rpms coming with OptimumCache

 

If got this error with ‘yum install optimumcache’:

 

Error: Package: cloudlinux-collect-0.1-6.el6.noarch (cloudlinux-x86_64-server-6)

Requires: perl(Config::Tiny)

Error: Package: cloudlinux-collect-0.1-6.el6.noarch (cloudlinux-x86_64-server-6)

Requires: perl(IO::Socket::SSL)

Error: Package: cloudlinux-collect-0.1-6.el6.noarch (cloudlinux-x86_64-server-6)

Requires: perl(YAML::Tiny)

Error: Package: cloudlinux-collect-0.1-6.el6.noarch (cloudlinux-x86_64-server-6)

Requires: perl(IPC::Run)

You could try using --skip-broken to work around the problem

You could try running: rpm -Va --nofiles --nodigest

 

Most probably you have excluded "perl*" packages in /etc/yum.conf file, in this case to install OptimumCache run:

 

# yum install optimumcache --disableexcludes=all

 

OptimumCache prior 0.2-23: Cannot unmount old ploop image

 

This is well-known ploop problem, which may result in failing such actions as resizing or moving ploop in OptimumCache. To workaround this problem use ‘--ignore-unmount-failure’ with --move-ploop:

 

# occtl --move-ploop --ignore-unmount-failure

 

As for resizing ploop, use flavor of ‘--move-ploop’ command instead:

 

# occtl --move-ploop /path/to/new/image/file [size GB] --ignore-unmount-failure

 

For your changes to take effect, the server has to be rebooted. Upon reboot, you may clean up manually old ploop image file and DiskDescriptor.xml file, which resides in the same directory along with old image.

 

High IO rate

 

High IO problem was fixed in latest version of OptimumCache (version 0.2-6). The fix is to eliminate superflows fsync() calls in OptimumCache operations. To activate this fix in existing installation, flag NOIMMSYNC=1 has to be manually set in /etc/syscoconfig/optimumcache.

 

To ensure that this parameter is set ON in the config, set LOGLEVEL=2 and execute ‘service optimumcache restart’. You will see something like this:

 

optimumcache[1770]: Hash-size: 100000000 min-size: 0 max-size: 18446744071562067968

optimumcache[1770]: Count: 0 Timeout: 5

optimumcache[1770]: Max Timeout: 160 Adaptive Timeout Mul/Div: 2/4

optimumcache[1770]: Iolimit: 0 iopslimit: 0

optimumcache[1770]: No immediate fsync: Yes

optimumcache[1771]: Starting OptimumCache monitor

 

To update to version 0.2-6 run:

 

# yum update optimumcache --enablerepo=cloudlinux-updates-testing

 

High CPU Utilization

 

Once it is detected that OptimumCache overuses CPU, it is useful to check, whether checksums reindexing process is running. When reindexing is running, high CPU usage is ok, as far it will certainly drop down after reindexing finished.

 

Can be checked in /var/log/messages -

 

# grep Reindexing /var/log/messages

Feb  4 17:00:55 CL-default-2 occtl[2654]: Reindexing started

 

If the last line from the output is not ‘Reindexing finished…”, than indexing is in progress.

 

Also, can be checked via command ‘occtl --report’, watch if PFL_REINDEX_NUM_FILES and PFL_REINDEX_THOUGHPUT_KB identifiers are present in the last series of data:

 

# occtl --report

- Period starts at: 2015-02-04 17:00

 Period Stat:

PFL_ATTACHED:

170318

PFL_CREATED:

161583

PFL_ERR_BAD_CSUM:

176

PFL_ERR_INODES:

879

PFL_FAILED_TO_ATTACH_PEER:

791

PFL_FAILED_TO_ATTACH_PEER_EBUSY:

791

PFL_INODE_IN:

406167

PFL_PAGEMIN_FILTERED_OUT:

233418

PFL_PAGEMIN_USED:

136082

PFL_REINDEX_NUM_FILES:

192810

PFL_REINDEX_THOUGHPUT_KB:

2904007

PFL_RESTART:

1

 

Uninstalling OptimumCache lasts for too long

 

Uninstalling OptimumCache takes time because of files unmark process, which lasts proportionally to number of files, previously marked for caching with ‘occtl --mark-dir...’. If you see, that ‘yum remove optimumcache’ command is stuck and you have no time to wait for it to finish, or IO load, caused by unmarking files, is undesirable for you, open another console terminal and invoke:

 

# occtl --cancel-pending-jobs

 

This command will cancel unmark operation, being run by yum under the hood. So that yum uninstall package transaction will complete very soon.

 

‘Failed to attach peer: Invalid argument’ appears in syslog

 

Rather rare problem, try to forcibly update optimumcache_s with ploop status.

 

# occtl --remount-cached-points