On Mon, Jan 21, 2013 at 11:36 PM, Peter Jeremy <pe...@rulingia.com> wrote: > On 2013-Jan-21 12:12:45 +0100, Wojciech Puchar < woj...@wojtek.tensor.gdynia.pl> wrote: >>While RAID-Z is already a king of bad performance, > > I don't believe RAID-Z is any worse than RAID5. Do you have any actual > measurements to back up your claim?
Leaving aside anecdotal evidence (or actual measurements), RAID-Z is fundamentally slower than RAID4/5 *for random reads*. This is because RAID-Z spreads each block out over all disks, whereas RAID5 (as it is typically configured) puts each block on only one disk. So to read a block from RAID-Z, all data disks must be involved, vs. for RAID5 only one disk needs to have its head moved. For other workloads (especially streaming reads/writes), there is no fundamental difference, though of course implementation quality may vary. >> Even better - use UFS. To each their own. As a ZFS developer, it should come as no surprise that in my opinion and experience, the benefits of ZFS almost always outweigh this downside. --matt _______________________________________________ freebsd-hackers@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to "freebsd-hackers-unsubscr...@freebsd.org"
