Hi,

I saw some interesting things with LVM and JFS the other day, i think
the JFS in this situation was reiserfs.

The system was a large x86 based server solution running Mandrake with
LVM + JFS and within this OS was VMwares GSX Server with multiple
Instances of Win2k (Although any OS in theory could be supported...)

In a 15 Second period, all instances of the operating environments
running within VMWare could be suspended, the logical volumes could be
quickly split off ( i am guessing it was a mirrored copy of an lvol and
the lvsplit command was used) the virtual systems were resumed, and the
split copies of the lvols were fs checked and mounted somewhere else for
backing up. All of this done with very little client downtime.

Once backed up the lvol could be remerged with the 'stale' copy of the
lvol and when it was time to backup again, it happens all over again...

I was pretty impressed, although, I would have to play a bit with it
myself to see how it really goes.. especially under high loads and to
see what the performance was like when you are readding the split mirror
copy to the VG, as it does thrash the disks heavily from what i have
seen under HP-UX.

Cheers,

Keiran




Brad Thomson wrote:

 > On Thu, 06 Dec 2001 15:03, Jill Rowling <[EMAIL PROTECTED]> wrote:
 >
 >
 >>On which filesystem? Were you using Linux EXT3 ..?
 >>
 >>One thing I'd like to try BTW is the new (to Solaris 8) "snap" 
feature for
 >>backup of a live UFS.
 >>I'm not sure that anyone has attempted to emulate that sort of thing 
yet on
 >>a journalling Linux filesystem.
 >>Basically it uses the journalling features of UFS to keep two effective
 >>journals running at once (or so I'm told), and the "snap" mount can 
just be
 >>deleted when you are finished with it. Though it apparently makes the 
system
 >>run slower when you are doing things.
 >>
 >
 > LVM enables you to take a snapshot of a live filesystem in this way.
 >
 > A while back when version control of properietary document formats was
 > discussed, I had the idea of having X days of snapshots available, 
and the
 > ability for a user to automount them via a Samba share if they needed to
 > access older revisions.
 >
 > I never did get around to trying it and promptly forgot about it, but I
 > can't see why it wouldn't work. I'm not *sure*, but I don't think LVM
 > snapshots require the physical size of the data on the parition to be
 > available for each snap.
 >
 > Brad.
 >
 >




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