[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-users] RE: AW: Best way to use iSCSI in domU
> -----Original Message----- > From: Ferenc Wagner [mailto:wferi@xxxxxxx] > Sent: Monday, June 22, 2009 8:55 AM > To: Jeff Sturm > Cc: xen-users@xxxxxxxxxxxxxxxxxxx > Subject: Re: AW: Best way to use iSCSI in domU > > Jeff Sturm <jeff.sturm@xxxxxxxxxx> writes: > > > We also use tap:sync: to ensure blocks are flushed to the SAN as > > they are written. If you have just one dom0 and could tolerate > > possible data loss, you're probably fine using phy: or tap:aio: > > instead. > > Doesn't phy: use direct IO (avoiding buffer cache) as well? Empirically, my guess is "no", or at least that writes are not performed synchronously. Our GFS cluster seems stable using tap:sync: as the backend, whereas it became corrupted on average once a week using phy:. We have since had 3 weeks of continuous uptime on the cluster. Frankly, I don't understand the kernel interfaces well enough to say for certain. I asked a question about this a few weeks ago on this list, and didn't receive a reply. If anyone knows for certain, it would be good to have confirmation, because I can't completely rule out some other cause of our fs corruption. -Jeff _______________________________________________ Xen-users mailing list Xen-users@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-users
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