[Lustre-discuss] MMP question

[Sebastian Reitenbach]

Hi,

I'm using Lustre 1.8.2 on SLES 11, with the following rpms installed:
lustre-ldiskfs-3.0.9-2.6.27.39_0.3_lustre.1.8.2_default
lustre-modules-1.8.2-2.6.27.39_0.3_lustre.1.8.2_default
kernel-default-extra-2.6.27.39-0.3_lustre.1.8.2
kernel-default-base-2.6.27.39-0.3_lustre.1.8.2
lustre-1.8.2-2.6.27.39_0.3_lustre.1.8.2_default
kernel-default-2.6.27.39-0.3_lustre.1.8.2
e2fsprogs-1.41.6.sun1-0suse

For the OSTs, I have SAN disks presented to two hosts. Reading the Manual 
"Using MMP" it states, that mmp gets enabled automatically when I use the --
failover parameter to specify the failover host. I have to admit, after 
formatting the OST, I did not checked whether it is enabled or not.
I manage Lustre mounting on the OST hosts via pacemaker, using the Lustre 
resource script, and it happened, that one of the OSTs was mounted on both 
hosts at the same time.

So I reformatted the OST this way:
mkfs.lustre --fsname=WBSTOR01 --ost --param="failover.node=192.168.24.22 at tcp" 
--mgsnode=192.168.8.150 at tcp --mkfsoptions="-m 0 -b 4096 -E stride=16" --
mountfsoptions="stripe=192,errors=remount-ro,extents,mballoc" --reformat 
/dev/lvm/WBOST01/WBOST01

And afterwards checking, dumpe2fs shows:
dumpe2fs -h /dev/lvm/WBOST01/WBOST01 | grep -i features
dumpe2fs 1.41.6.sun1 (30-May-2009)                               
Filesystem features:      has_journal ext_attr resize_inode dir_index filetype 
extent sparse_super large_file uninit_bg

The manual says, MMP is activated automatically on new filesystems, and I 
thought it has been a new filesystem, also when I use the --reformat 
parameter.

Now I enabled MMP manually:
tune2fs -O mmp /dev/lvm/WBOST01/WBOST01
And I also see the option testing for it:
dumpe2fs -h /dev/lvm/WBOST01/WBOST01 | grep -i features
dumpe2fs 1.41.6.sun1 (30-May-2009)
Filesystem features:      has_journal ext_attr resize_inode dir_index filetype 
needs_recovery extent mmp sparse_super large_file uninit_bg

And I see MMP working, mounting it on the first server prevents a second mount 
on the other at the same time.

So I am wondering whether I missed sth.?

regards,
Sebastian