Le 18/05/2013 ? 09:02:15-0400, Paul Kraus a écrit > On May 18, 2013, at 3:21 AM, Ivailo Tanusheff > <ivailo.tanush...@skrill.com> wrote: > > > If you use HBA/JBOD then you will rely on the software RAID of the > > ZFS system. Yes, this RAID is good, but unless you use SSD disks to > > boost performance and a lot of RAM the hardware raid should be more > > reliable and mush faster. > > Why will the hardware raid be more reliable ? While hardware raid is > susceptible to uncorrectable errors from the physical drives > (hardware raid controllers rely on the drives to report bad reads and > writes), and the uncorrectable error rate for modern drives is such > that with high capacity drives (1TB and over) you are almost certain > to run into a couple over the operational life of the drive. 10^-14 > for cheap drives and 10^-15 for better drives, very occasionally I > see a drive rated for 10^-16. Run the math and see how many TB worth > of data you have to write and read (remember these failures are > generally read failures with NO indication that a failure occurred, > bad data is just returned to the system). > > In terms of performance HW raid is faster, generally due to the cache > RAM built into the HW raid controller. ZFS makes good use of system,
Before I'm installing my server under 9.0 + ZFS I do some benchmarks with ionice to compare FreeBSD 9.0+ ZFS + 12 disk SATA 7200 rpm vs CentOS + H700 + 12 disk SAS 15krpm (Both are same Dell poweredge). And the ZFS+12 disk sata goes much faster than CentOS+H700+ext4 almost everywhere. Only for small file AND small record size the ZFS is slower than CentOS. The server don't have SSD. He got 48Go of ram. Regards. JAS -- Albert SHIH DIO bâtiment 15 Observatoire de Paris 5 Place Jules Janssen 92195 Meudon Cedex France Téléphone : +33 1 45 07 76 26/+33 6 86 69 95 71 xmpp: j...@obspm.fr Heure local/Local time: jeu 23 mai 2013 10:53:50 CEST _______________________________________________ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to "freebsd-questions-unsubscr...@freebsd.org"