Hi
I am very new to lustre file system.
I want to know how can I test whether the failover is working or not?
I am having the following scenario of lustre file system--
MGS- /dev/sdb on node1 and failnode node2
MDT- /dev/sdc on node1 and failnode node2
(I am using iSCSI for the sharing discs /dev/sdb & /dev/sdc between node1
& node2)
OST1- /dev/sda1 on node2
OST2- /dev/sda2 on node2
And there are 3 clients.
If client1 opens a file to write and at that time if I umount the MDT (which
will be mounted on node1) will node2 take care of? Will client1 experience any
difference?
-Trupti
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Hi Trupti, It depends on how your failover is implemented. The bottom line is that if you have a transaction in-flight when your MDT is disconnected, all new transactions will block until queued and in-flight transactions either complete or time out. If your failover window is a few seconds or less, you shouldn?t notice more than a minor blip as the failover MDS recovers state for the downed MDS and finishes any transactions in progress. Your results will vary depending on the hardware you use and the settings of your failover; in one of my clusters, my failover window is actually quite long (about a minute and a half) due to the way the storage is implemented (the FC buses spend considerable time polling each visible LUN looking for the Lustre ones and I never bothered with device multi-pathing), but my transactions complete as expected once the MDT becomes active on the failover MDS. cheers, Klaus On 6/11/08 5:07 AM, "trupti shete" <truptips86 at yahoo.co.in>did etch on stone tablets:> Hi > I am very new to lustre file system. > I want to know how can I test whether the failover is working or not? > > I am having the following scenario of lustre file system-- > MGS- /dev/sdb on node1 and failnode node2 > MDT- /dev/sdc on node1 and failnode node2 > (I am using iSCSI for the sharing discs /dev/sdb & /dev/sdc between node1 & > node2) > OST1- /dev/sda1 on node2 > OST2- /dev/sda2 on node2 > And there are 3 clients. > > If client1 opens a file to write and at that time if I umount the MDT (which > will be mounted on node1) will node2 take care of? Will client1 experience any > difference? > > -Trupti > > > > Explore your hobbies and interests. Click here to begin. > <http://in.rd.yahoo.com/tagline_groups_6/*http://in.promos.yahoo.com/groups/> > > _______________________________________________ > Lustre-discuss mailing list > Lustre-discuss at lists.lustre.org > http://lists.lustre.org/mailman/listinfo/lustre-discuss-------------- next part -------------- An HTML attachment was scrubbed... URL: http://lists.lustre.org/pipermail/lustre-discuss/attachments/20080612/5f722ffc/attachment.html
On Wed, Jun 11, 2008 at 01:07:56PM +0100, trupti shete wrote:> I am having the following scenario of lustre file system-- > MDT- /dev/sdc on node1 and failnode node2[...]> If client1 opens a file to write and at that time if I umount the MDT (which > will be mounted on node1) will node2 take care of?Just in case it is not clear, you need to remount the mdt on node2 by hand or configure an external HA software (like Heartbeat/linux-HA) to manage the failover. http://manual.lustre.org/manual/LustreManual16_HTML/Failover.html#50446391_pgfId-5529 Johann
On Jun 13, 1:53 pm, Johann Lombardi <joh... at sun.com> wrote:> On Wed, Jun 11, 2008 at 01:07:56PM +0100, trupti shete wrote: > > I am having the following scenario of lustre file system-- > > MDT- /dev/sdc on node1 and failnode node2 > [...] > > If client1 opens a file to write and at that time if I umount the MDT (which > > will be mounted on node1) will node2 take care of? > > Just in case it is not clear, you need to remount the mdt on node2 by hand > or configure an external HA software (like Heartbeat/linux-HA) to manage the > failover.Is HA software compulsory? Does lustre inherently provides some mechanism?> > http://manual.lustre.org/manual/LustreManual16_HTML/Failover.html#504... > > Johann > _______________________________________________ > Lustre-discuss mailing list > Lustre-disc... at lists.lustre.orghttp://lists.lustre.org/mailman/listinfo/lustre-discuss
On Thu, 2008-06-26 at 21:25 -0700, Dhruv wrote:> > On Jun 13, 1:53 pm, Johann Lombardi <joh... at sun.com> wrote: > > On Wed, Jun 11, 2008 at 01:07:56PM +0100, trupti shete wrote: > > > I am having the following scenario of lustre file system-- > > > MDT- /dev/sdc on node1 and failnode node2 > > [...] > > > If client1 opens a file to write and at that time if I umount the MDT (which > > > will be mounted on node1) will node2 take care of? > > > > Just in case it is not clear, you need to remount the mdt on node2 by hand > > or configure an external HA software (like Heartbeat/linux-HA) to manage the > > failover. > > Is HA software compulsory? Does lustre inherently provides some > mechanism?Lustre filesystem only supports failover at the server level. Lustre does not have a complete failover solution which includes failure detection, power control, etc. So you need an external HA mechanism like Heartbeat which can detect the failure of the primary server and control the failover. This HA software will control Lustre with a provided service script (which will mount the OST or MDT on the secondary node) The link provided below should answer most of your questions about Lustre failover:> > > > http://manual.lustre.org/manual/LustreManual16_HTML/Failover.html#504... > >Thanks, Kalpak