FC RAID array -- One writer, Many Readers?

jason andrade jason at rtfmconsult.com
Thu Oct 30 15:16:01 CST 2003


On Thu, 30 Oct 2003, Jake Gold wrote:

> I have a FC RAID array with 5 machines (with FC HBAs) connected to it.
> All 5 servers see this "drive" (as a SCSI device - using the QLogic driver).

fun..

> I want to "serve" (read: read) the same data from all 5 servers, but only allow one server to write to it:
>
> 4 servers read-only
> 1 server read-write

the problem i looked at 3+ years ago.  wasn't really a solution then and i don't think
there is one now.

> I'm well aware of (and have used) GFS for this exact scenario, but it strikes me as overkill.
>
> And I could, of course, create an ext3 file system on the shared disk. I would be able to mount it properly, but changes to the file system would not be
> propagated to the read-only servers. So this is a big problem obviously.

yes.  the read servers would probably crash or behave very strangely.

> Is anyone aware of something a bit more than a simple file system (or a standard configuration of one, I should say) but less than a full-blown Cluster FS like GFS?

you could try talking to veritas as they may have a cluster aware filesystem
for linux.

> Or maybe another solution to this?

sgi may have a cluster aware filesystem too - cxfs so perhaps some
research there.

> (I'm using Linux on Dell servers, so that's how I rationalize asking this list ;-)
> I also could not find any list that seemed more appropriate, but I would welcome a referral.)

please let us know how you go - this has been a problem in linux for a while and
it'd be great to know there is a FC level solution (apart from GFS).

till now i have gotten around it by using a network protocol instead, e.g
NFS (and some people have used CODA or other such methods)

regards,

-jason




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