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Re: multiple machines mounting same partition via SAN

To: daves@xxxxxxxxxxxxxxx
Subject: Re: multiple machines mounting same partition via SAN
From: Steve Lord <lord@xxxxxxx>
Date: Fri, 28 Jan 2005 14:19:05 -0600
Cc: linux-xfs@xxxxxxxxxxx
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David Sparks wrote:
I'm testing a new SAN here ... I connected 2 machines and both mounted the same partition in R/W mode. I was expecting something like this to happen:

xfs_force_shutdown(sdb1,0x1) called from line 353 of file fs/xfs/xfs_rw.c. Return address = 0xffffffff80202e0b
Filesystem "sdb1": I/O Error Detected.  Shutting down filesystem: sdb1
Please umount the filesystem, and rectify the problem(s)
xfs_force_shutdown(sdb1,0x1) called from line 353 of file fs/xfs/xfs_rw.c. Return address = 0xffffffff80202e0b

Ok, good.

What I'm actually interested in is having one machine mount the partition in RW and another in RO mode. Is this a sane configuration?

Thanks,

ds


Nope

Each host caches metadata and filedata in memory. Once the RW machine has
modified metadata or data, what is going to tell the RO machine that things
have changed and that cached information is stale? In pretty short order you
are going to hit the same sort of error as in the above case.

It is either read only everywhere, or you go buy a commercial shared
fs, or look at gfs and what ever else may be out there.

Steve


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