On 20 jan 2010, at 17.22, Julian Regel wrote: > >It is actually not that easy. > > > >Compare a cost of 2x x4540 with 1TB disks to equivalent solution on LTO. > > > >Each x4540 could be configured as: 4x 11 disks in raidz-2 + 2x hot spare > >+ 2x OS disks. > >The four raidz2 group form a single pool. This would provide well over > >30TB of logical storage per each box. > > > >Now you rsync all the data from your clients to a dedicated filesystem > >per client, then create a snapshot. > >All snapshots are replicated to a 2nd x4540 so even if you would loose > >entire box/data for some reason you would still have a spare copy. > > > >Now compare it to a cost of a library, lto drives, tapes, software + > >licenses, support costs, ... > > > >See more details at > >http://milek.blogspot.com/2009/12/my-presentation-at-losug.html > > I've just read your presentation Robert. Interesting stuff. > > I've also just done a pen and paper exercise to see how much 30TB of tape > would cost as a comparison to your disk based solution. > > Using list prices from Sun's website (and who pays list..?), an SL48 with 2 x > LTO3 drives would cost £14000. I couldn't see a price on an LTO4 equipped > SL48 despite the Sun website saying it's a supported option. Each LTO3 has a > native capacity of 300GB and the SL48 can hold up to 48 tapes in the library > (14.4TB native per library). To match the 30TB in your solution, we'd need > two libraries totalling £28000.
LTO3 has native capacity 400 GB, LTO4 has 800. The price is about the same per tape and per drive, a little higher for LTO4. > You would also need 100 LTO3 tapes to provide 30TB of native storage. I > recently bought a pack of 20 tapes for £340, so five packs would be £1700. Or rather 37 LTO4 tapes, and only one 48 tape library. But that doesn't matter, the interesting part is that one now can use whatever best solves the problem at hand. > So you could provision a tape backup for just under £30000 (~$49000). In > comparison, the cost of one X4540 with ~ 36TB usable storage is UK list price > £30900. I've not factored in backup software since you could use an open > source solution such as Amanda or Bacula. > > Which isn't to say tape would be a "better" solution since it's going to be > slower to restore etc. But it does show that tape can work out cheaper, > especially since the cost of a high speed WAN link isn't required. Reading from tape is normally faster than reading from (a single) disk. Seek time of course isn't. /ragge _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
