Hi Dewey, Yes, I meant that ZFS scales linearly with the number of spindles, essentially being able to drive them at their max throughput. I'm not sure on your RAID 6 calculation. For reads certainly you'd scale with number of spindles (basically a striped read). For writes, without cache, you would certainly see a large decrease from that in general. ZFS, for asynchronous I/O, essentially always tries to do sequential full-stripe writes even of random-write data, greatly improving over random performance. If it's synchronous writes it has to get them out to disk fast, and that's when the logzilla really improves performance.
--Peter Blogs: http://ctistrategy.com http://www.galvin.info On 4/3/09 3:59 PM, "Dewey Sasser" <[email protected]> wrote: > Peter Galvin wrote: > >>> ZFS will go at spindle speed for sequential I/O. For random I/O it's best to >>> have flash memory for the ZIL (intent log). I assume you'd use NFS if you >>> went with an external device? If so that would be mostly random I/O and >>> you'd want the ZIL to be on flash. >> > > "Spindle speed" is an interesting concept. I know I need to go way > faster than a single spindle will give me. I have an idea of how > various RAIDs scale with number of spindles, but how does ZFS do? If I > buy a 7210 with 46 drives, do I effectively see 46 * (1 drive's worth of > IOps)? With RAID 6 I would expect 1/6*46*(1 drive's worth of IOps). > > thanks, > > -- > Dewey > > > _______________________________________________ > bblisa mailing list > [email protected] > http://www.bblisa.org/mailman/listinfo/bblisa _______________________________________________ bblisa mailing list [email protected] http://www.bblisa.org/mailman/listinfo/bblisa
