Hi, Bob Friesenhahn wrote: > On Wed, 22 Oct 2008, Neil Perrin wrote: >> On 10/22/08 10:26, Constantin Gonzalez wrote: >>> 3. Disable ZIL[1]. This is of course evil, but one customer pointed out to >>> me >>> that if a tar xvf were writing locally to a ZFS file system, the writes >>> wouldn't be synchronous either, so there's no point in forcing NFS users >>> to having a better availability experience at the expense of >>> performance. > > The conclusion reached here is quite seriously wrong and no Sun > employee should suggest it to a customer. If the system writing to a
I'm not suggesting it to any customer. Actually, I argued quite a long time with the customer, trying to convince him that "slow but correct" is better. The conclusion above is a conscious decision by the customer. He says that he does not want NFS to turn any write into a synchronous write, he's happy if all writes are asynchronous, because in this case the NFS server is a backup to disk device and if power fails he simply restarts the backup 'cause he has the data in multiple copies anyway. > local filesystem reboots then the applications which were running are > also lost and will see the new filesystem state when they are > restarted. If an NFS server sponteneously reboots, the applications > on the many clients are still running and the client systems are using > cached data. This means that clients could do very bad things if the > filesystem state (as seen by NFS) is suddenly not consistent. One of > the joys of NFS is that the client continues unhindered once the > server returns. Yes, we're both aware of this. In this particular situation, the customer would restart his backup job (and thus the client application) in case the server dies. Thanks for pointing out the difference, this is indeed an important distinction. Cheers, Constantin -- Constantin Gonzalez Sun Microsystems GmbH, Germany Principal Field Technologist http://blogs.sun.com/constantin Tel.: +49 89/4 60 08-25 91 http://google.com/search?q=constantin+gonzalez Sitz d. Ges.: Sun Microsystems GmbH, Sonnenallee 1, 85551 Kirchheim-Heimstetten Amtsgericht Muenchen: HRB 161028 Geschaeftsfuehrer: Thomas Schroeder, Wolfgang Engels, Dr. Roland Boemer Vorsitzender des Aufsichtsrates: Martin Haering _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
