On Thu, 3 Jul 2008, Don Enrique wrote: > > This means that i potentially could loose 40TB+ of data if three > disks within the same RAIDZ-2 vdev should die before the resilvering > of at least one disk is complete. Since most disks will be filled i > do expect rather long resilvering times.
Yes, this risk always exists. The probability of three disks independently dying during the resilver is exceedingly low. The chance that your facility will be hit by an airplane during resilver is likely higher. However, it is true that RAIDZ-2 does not offer the same ease of control over physical redundancy that mirroring does. If you were to use 10 independent chassis and split the RAIDZ-2 uniformly across the chassis then the probability of a similar calamity impacting the same drives is driven by rack or facility-wide factors (e.g. building burning down) rather than shelf factors. However, if you had 10 RAID arrays mounted in the same rack and the rack falls over on its side during resilver then hope is still lost. I am not seeing any options for you here. ZFS RAIDZ-2 is about as good as it gets and if you want everything in one huge pool, there will be more risk. Perhaps there is a virtual filesystem layer which can be used on top of ZFS which emulates a larger filesystem but refuses to split files across pools. In the future it would be useful for ZFS to provide the option to not load-share across huge VDEVs and use VDEV-level space allocators. Bob ====================================== Bob Friesenhahn [EMAIL PROTECTED], http://www.simplesystems.org/users/bfriesen/ GraphicsMagick Maintainer, http://www.GraphicsMagick.org/ _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
