Chris Cosby wrote: >I'm going down a bit of a different path with my reply here. I know that all >shops and their need for data are different, but hear me out. > >1) You're backing up 40TB+ of data, increasing at 20-25% per year. That's >insane. Perhaps it's time to look at your backup strategy no from a hardware >perspective, but from a data retention perspective. Do you really need that >much data backed up? There has to be some way to get the volume down. If >not, you're at 100TB in just slightly over 4 years (assuming the 25% growth >factor). If your data is critical, my recommendation is to go find another >job and let someone else have that headache.
Well, we are talking about backup for ~900 servers that are in production. Our retention period is 14 days for stuff like web servers, and 3 weeks for SQL and such. We could deploy deduplication but it makes me a wee bit uncomfortable to blindly trust our backup software. >2) 40TB of backups is, at the best possible price, 50-1TB drives (for spares >and such) - $12,500 for raw drive hardware. Enclosures add some money, as do >cables and such. For mirroring, 90-1TB drives is $22,500 for the raw drives. >In my world, I know yours is different, but the difference in a $100,000 >solution and a $75,000 solution is pretty negligible. The short description >here: you can afford to do mirrors. Really, you can. Any of the parity >solutions out there, I don't care what your strategy, is going to cause you >more trouble than you're ready to deal with. Good point. I'll take that into consideration. >I know these aren't solutions for you, it's just the stuff that was in my >head. The best possible solution, if you really need this kind of volume, is >to create something that never has to resilver. Use some nifty combination >of hardware and ZFS, like a couple of somethings that has 20TB per container >exported as a single volume, mirror those with ZFS for its end-to-end >checksumming and ease of management. > >That's my considerably more than $0.02 > >On Thu, Jul 3, 2008 at 11:56 AM, Bob Friesenhahn < >[EMAIL PROTECTED]> wrote: > >> 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 >> > > > >-- >chris -at- microcozm -dot- net >=== Si Hoc Legere Scis Nimium Eruditionis Habes -- Med venlig hilsen / Best Regards Henrik Johansen [EMAIL PROTECTED] _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
