2010/1/12 Rafał Jackiewicz <free...@o2.pl>: >>Thanks, could you do the same, but using 2 .eli vdevs mirrorred >>together in a zfs mirror? >> >>- Sincerely, >>Dan Naumov > > Hi, > > Proc: Intell Atom 330 (2x1.6Ghz) - 1 package(s) x 2 core(s) x 2 HTT threads > Chipset: Intel 82945G > Sys: 8.0-RELEASE FreeBSD 8.0-RELEASE #0 > empty file: /boot/loader.conf > Hdd: > ad4: 953869MB <Seagate ST31000533CS SC15> at ata2-master SATA150 > ad6: 953869MB <Seagate ST31000533CS SC15> at ata3-master SATA150 > Geli: > geli init -s 4096 -K /etc/keys/ad4s2.key /dev/ad4s2 > geli init -s 4096 -K /etc/keys/ad6s2.key /dev/ad6s2 > > > Results: > **************************************************** > > *** single drive write MB/s read MB/s > eli.journal.ufs2 23 14 > eli.zfs 19 36 > > > *** mirror write MB/s read MB/s > mirror.eli.journal.ufs2 23 16 > eli.zfs 31 40 > zfs 83 79 > > > *** degraded mirror write MB/s read MB/s > mirror.eli.journal.ufs2 16 9 > eli.zfs 56 40 > zfs 86 71 > > ****************************************************
Thanks a lot for your numbers, the relevant part for me was this: *** mirror write MB/s read MB/s eli.zfs 31 40 zfs 83 79 *** degraded mirror write MB/s read MB/s eli.zfs 56 40 zfs 86 71 31 mb/s writes and 40 mb/s reads is something that I guess I could potentially live with. I am guessing the main problem of stacking ZFS on top of geli like this is the fact that writing to a mirror requires double the CPU use, because we have to encrypt all written data twice (once to each disk) instead of encrypting first and then writing the encrypted data to 2 disks as would be the case if we had crypto sitting on top of ZFS instead of ZFS sitting on top of crypto. I now have to reevaluate my planned use of an SSD though, I was planning to use a 40gb partition on an Intel 80GB X25-M G2 as a dedicated L2ARC device for a ZFS mirror of 2 x 2tb disks. However these numbers make it quite obvious that I would already be CPU-starved at 40-50mb/s throughput on the encrypted ZFS mirror, so adding an l2arc SSD, while improving latency, would do really nothing for actual disk read speeds, considering the l2arc itself would too, have to sit on top of a GELI device. - Sincerely, Dan Naumov _______________________________________________ freebsd-stable@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-stable To unsubscribe, send any mail to "freebsd-stable-unsubscr...@freebsd.org"
