[Lustre-discuss] MMP question

[Brian J. Murrell]

On Mon, 2010-03-29 at 10:49 +0100, Sebastian Reitenbach wrote: 
> Hi,

Hi,

> mmp gets enabled automatically when I use the --
> failover parameter to specify the failover host.

Indeed.

> 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

...when they are formatted with the --failnode option set.  You didn't
use the --failnode option.  You set the failover.node parameter.

Having not looked at the actual code, I'd guess that only the --failnode
option sets MMP and parameters are not considered for the purpose of MMP
setting.

The moral of the story is to use --failnode, not set the failover.node
parameter when formatting filesystem.  And file a bug about lack of MMP
when setting the parameter instead of using --failnode.  :-)

b.

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