Well actually... raidz2: - 7x 1.5 tb = 10.5tb - 2 parity drives
raidz1: - 3x 1.5 tb = 4.5 tb - 4x 1.5 tb = 6 tb , total 10.5tb - 2 parity drives in split thus different raidz1 arrays So really, in both cases 2 different parity drives and same storage... --- Fleuriot Damien On 5 Jan 2011, at 16:55, Chris Forgeron <cforge...@acsi.ca> wrote: > First off, raidz2 and raidz1 with copies=2 are not the same thing. > > raidz2 will give you two copies of parity instead of just one. It also > guarantees that this parity is on different drives. You can sustain 2 drive > failures without data loss. > > raidz1 with copies=2 will give you two copies of all your files, but there is > no guarantee that they are on different drives, and you can still only > sustain 1 drive failure. > > You'll have better space efficiency with raidz2 if you're using 9 drives. > > If I were you, I'd use your 9 disks as one big raidz, or better yet, get 10 > disks, and make a stripe of 2 5 disk raidz's for the best performance. > > Save your SSD drive for the L2ARC (cache) or ZIL, you'll get better speed > that way instead of throwing it away on a boot drive. > > -- > > > -----Original Message----- > From: owner-freebsd-sta...@freebsd.org > [mailto:owner-freebsd-sta...@freebsd.org] On Behalf Of Damien Fleuriot > Sent: January-05-11 5:01 AM > To: Damien Fleuriot > Cc: freebsd-stable@freebsd.org > Subject: Re: ZFS - moving from a zraid1 to zraid2 pool with 1.5tb disks > > Hi again List, > > I'm not so sure about using raidz2 anymore, I'm concerned for the performance. > > Basically I have 9x 1.5T sata drives. > > raidz2 and 2x raidz1 will provide the same capacity. > > Are there any cons against using 2x raidz1 instead of 1x raidz2 ? > > I plan on using a SSD drive for the OS, 40-64gb, with 15 for the system > itself and some spare. > > Is it worth using the free space for cache ? ZIL ? both ? > > @jean-yves : didn't you experience problems recently when using both ? > > --- > Fleuriot Damien > > On 3 Jan 2011, at 16:08, Damien Fleuriot <m...@my.gd> wrote: > >> >> >> On 1/3/11 2:17 PM, Ivan Voras wrote: >>> On 12/30/10 12:40, Damien Fleuriot wrote: >>> >>>> I am concerned that in the event a drive fails, I won't be able to >>>> repair the disks in time before another actually fails. >>> >>> An old trick to avoid that is to buy drives from different series or >>> manufacturers (the theory is that identical drives tend to fail at >>> the same time), but this may not be applicable if you have 5 drives >>> in a volume :) Still, you can try playing with RAIDZ levels and >>> probabilities. >>> >> >> That's sound advice, although one also hears that they should get >> devices from the same vendor for maximum compatibility -.- >> >> >> Ah well, next time ;) >> >> >> A piece of advice I shall heed though is using 1% less capacity than >> what the disks really provide, in case one day I have to swap a drive >> and its replacement is a few kbytes smaller (thus preventing a rebuild). > _______________________________________________ > 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" _______________________________________________ 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"
