Date: Wed, 5 Jan 2011 10:01:11 +0100 From: Damien Fleuriot <ml@my.gd> To: Damien Fleuriot <ml@my.gd> Cc: "freebsd-stable@freebsd.org" <freebsd-stable@freebsd.org> Subject: Re: ZFS - moving from a zraid1 to zraid2 pool with 1.5tb disks Message-ID: <84882169-0461-480F-8B4C-58E794BCC8E6@my.gd> In-Reply-To: <4D21E679.80002@my.gd> References: <4D1C6F90.3080206@my.gd> <ifsia5$5ub$2@dough.gmane.org> <4D21E679.80002@my.gd>
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Hi again List, I'm not so sure about using raidz2 anymore, I'm concerned for the performanc= e. 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 itse= lf 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 <ml@my.gd> wrote: >=20 >=20 > On 1/3/11 2:17 PM, Ivan Voras wrote: >> On 12/30/10 12:40, Damien Fleuriot wrote: >>=20 >>> 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. >>=20 >> 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.= >>=20 >=20 > That's sound advice, although one also hears that they should get > devices from the same vendor for maximum compatibility -.- >=20 >=20 > Ah well, next time ;) >=20 >=20 > 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).
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