Andreas, Is the mmp feature already in the existing Lustre distribution? If so, what versions are mmp-aware? If not, which version will be the first to incorporate it?
thanks, Klaus On 3/10/08 2:15 PM, "Andreas Dilger" <[EMAIL PROTECTED]>did etch on stone tablets: > On Mar 10, 2008 09:09 -0600, Colin Faber wrote: >> Is this true even in the case of mounting the OSS as a read only node? > > Yes, definitely even a "read only" mount can cause serious corruption. > There are several issues involved, the most dangerous is that even for > read-only mounting the journal is replayed by the kernel or otherwise > the filesystem may appear to be corrupted. > > In addition, there is the problem that (meta)data that is cached on the > read-only mounting node will become incorrect as the writing node is > changing the filesystem. The ext3 filesystem is not cluster aware. > > In order to prevent situations like this, the newer releases of ldiskfs > and e2fsprogs have an "mmp" (multi-mount protection) feature which will > prevent the filesystem to be mounted on another node if it is active > on one node (either mounted, or running e2fsck). > > This will be enabled by default on newly-formatted filesystems which > are created with the "--failover" flag, and can also be enabled by > hand with "tune2fs -O mmp /dev/XXXX" (replace with MDT or OST device > names as appropriate). This will prevent the filesystem from being > mounted or e2fsck'd by old kernels/e2fsprogs so it isn't enabled by > default on existing filesystems. > >> Andreas Dilger wrote: >>> On Mar 07, 2008 00:04 +0530, Neeladri Bose wrote: >>> >>>> To address the performance hit (whatever be the %age) if we setup DRDB in >>>> active-passive mode across the 4500's but have the LustreFS points to >>>> separate raid sets from the network across the DRDB pair of 4500's & thus >>>> become an active-active solution which may actually increase the >>>> throughput of the LustreFS. >>>> >>>> Can it be a possible scenario using DRDB on Linux with ext3 & LustreFS? >>>> >>> >>> No, Lustre does not support active-active export of backing filesystems. >>> This doesn't work because the backing filesystems (ext3/ZFS) are not >>> themselves cluster-aware and mounting them on two nodes will quickly >>> lead to whole filesystem corruption. > > Cheers, Andreas > -- > Andreas Dilger > Sr. Staff Engineer, Lustre Group > Sun Microsystems of Canada, Inc. > > _______________________________________________ > 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
