Its an issue with ext[34]. Take a look at http://jira.whamcloud.com/browse/LU-15 for more details.
Jeremy On Wed, Apr 20, 2011 at 8:28 AM, James Rose <[email protected]>wrote: > Hi Kevin, > > Thanks for the suggestion. I will try this out. > > For the moment it seems that it may be disk space related. I have > removed some data from the file system. Performance returned to where I > would expect it to be as space freed up (currently at 83% full). Since > free space I have seen two messages on an OSS where the number of > threads is tuned to the amount of RAM in the host and six on an OSS that > has the number of threads set higher than it should. This is a much > better situation than the steady stream I was experiencing last night. > Maybe disabling the read cache will remove the last few. > > I am still very curious what the rapid small reads seen when writing are > as this showed up while mounted ldiskfs so not doing regular lustre > operations at all. > > Thanks again for your help, > > James. > > > On Wed, 2011-04-20 at 08:48 -0300, Kevin Van Maren wrote: > > First guess is the increased memory pressure caused by the Lustre 1.8 > > read cache. Many times "slow" messages are caused by memory > > allocatons taking a long time. > > > > You could try disabling the read cache and see if that clears up the > > slow messages. > > > > Kevin > > > > > > On Apr 20, 2011, at 4:29 AM, James Rose <[email protected]> > > wrote: > > > > > Hi > > > > > > We have been experiencing degraded performance for a few days on a > > > fresh install of lustre 1.8.5 (on RHEL5 using sun ext4 rpms). The > > > initial bulk load of the data will be fine but once in use for a > > > while writes become very slow to individual ost. This will block io > > > for a few minutes and then carry on as normal. The slow writes will > > > then move to another ost. This can be seen in iostat and many slow > > > IO messages will be seen in the logs (example included) > > > > > > The osts are between 87 90 % full. Not ideal but has not caused any > > > issues running 1.6.7.2 on the same hardware. > > > > > > The osts are RAID6 on external raid chassis (Infortrend). Each ost > > > is 5.4T (small). The server is Dual AMD (4 cores). 16G Ram. Qlogic > > > FC HBA. > > > > > > I mounted the osts as ldiskfs and tried a few write tests. These > > > also show the same behaviour. > > > > > > While the write operation is blocked there will be hundreds of read > > > tps and a very small kb/s read from the raid but now writes. As > > > soon as this completes writes will go through at a more expected > > > speed. > > > > > > Any idea what is going on? > > > > > > Many thanks > > > > > > James. > > > > > > Example error messages: > > > > > > Apr 20 04:53:04 oss5r-mgmt kernel: LustreError: dumping log to /tmp/ > > > lustre-log.1303271584.3935 > > > Apr 20 04:53:40 oss5r-mgmt kernel: Lustre: rho-OST0012: slow quota > > > init 286s due to heavy IO load > > > Apr 20 04:53:40 oss5r-mgmt kernel: Lustre: rho-OST0012: slow journal > > > start 39s due to heavy IO load > > > Apr 20 04:53:40 oss5r-mgmt kernel: Lustre: Skipped 39 previous > > > similar messages > > > Apr 20 04:53:40 oss5r-mgmt kernel: Lustre: rho-OST0012: slow > > > brw_start 39s due to heavy IO load > > > Apr 20 04:53:40 oss5r-mgmt kernel: Lustre: Skipped 38 previous > > > similar messages > > > Apr 20 04:53:40 oss5r-mgmt kernel: Lustre: rho-OST0012: slow journal > > > start 133s due to heavy IO load > > > Apr 20 04:53:40 oss5r-mgmt kernel: Lustre: Skipped 44 previous > > > similar messages > > > Apr 20 04:53:40 oss5r-mgmt kernel: Lustre: rho-OST0012: slow > > > brw_start 133s due to heavy IO load > > > Apr 20 04:53:40 oss5r-mgmt kernel: Lustre: Skipped 44 previous > > > similar messages > > > Apr 20 04:53:40 oss5r-mgmt kernel: Lustre: rho-OST0012: slow journal > > > start 236s due to heavy IO load > > > Apr 20 04:53:40 oss5r-mgmt kernel: Lustre: rho-OST0012: slow i_mutex > > > 40s due to heavy IO load > > > Apr 20 04:53:40 oss5r-mgmt kernel: Lustre: Skipped 2 previous > > > similar messages > > > Apr 20 04:53:40 oss5r-mgmt kernel: Lustre: Skipped 6 previous > > > similar messages > > > Apr 20 04:53:40 oss5r-mgmt kernel: Lustre: rho-OST0012: slow i_mutex > > > 277s due to heavy IO load > > > Apr 20 04:53:40 oss5r-mgmt kernel: Lustre: rho-OST0012: slow > > > direct_io 286s due to heavy IO load > > > Apr 20 04:53:40 oss5r-mgmt kernel: Lustre: Skipped 3 previous > > > similar messages > > > Apr 20 04:53:40 oss5r-mgmt kernel: Lustre: rho-OST0012: slow journal > > > start 285s due to heavy IO load > > > Apr 20 04:53:40 oss5r-mgmt kernel: Lustre: Skipped 1 previous > > > similar message > > > Apr 20 04:53:40 oss5r-mgmt kernel: Lustre: rho-OST0012: slow > > > commitrw commit 285s due to heavy IO load > > > Apr 20 04:53:40 oss5r-mgmt kernel: Lustre: Skipped 1 previous > > > similar message > > > Apr 20 04:53:40 oss5r-mgmt kernel: Lustre: rho-OST0012: slow parent > > > lock 236s due to heavy IO load > > > > > > > > > _______________________________________________ > > > Lustre-discuss mailing list > > > [email protected] > > > http://lists.lustre.org/mailman/listinfo/lustre-discuss > > _______________________________________________ > > Lustre-discuss mailing list > > [email protected] > > http://lists.lustre.org/mailman/listinfo/lustre-discuss > > > _______________________________________________ > Lustre-discuss mailing list > [email protected] > http://lists.lustre.org/mailman/listinfo/lustre-discuss >
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