Date: Thu, 06 Jan 2011 07:26:32 -0400 From: Chris Forgeron <cforgeron@acsi.ca> To: Damien Fleuriot <ml@my.gd>, Artem Belevich <fbsdlist@src.cx> 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: <BEBC15BA440AB24484C067A3A9D38D7E0149F32D33F9@server7.acsi.ca> In-Reply-To: <CC37553B-EE13-4B5B-AC87-80D0ECC1A2B3@my.gd> References: <4D1C6F90.3080206@my.gd> <ifsia5$5ub$2@dough.gmane.org> <4D21E679.80002@my.gd> <84882169-0461-480F-8B4C-58E794BCC8E6@my.gd> <BEBC15BA440AB24484C067A3A9D38D7E0149F32D13E3@server7.acsi.ca> <488AE93A-97B9-4F01-AD0A-0098E4B329C3@my.gd> <AANLkTimezasVY%2BMJjWn2T9sBGQV-JrNmYqRwv_gPYPJP@mail.gmail.com> <CC37553B-EE13-4B5B-AC87-80D0ECC1A2B3@my.gd>
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You know, these days I'm not as happy with SSD's for ZIL. I may blog about some of the speed results I've been getting over the last 6mo-1yr that I've been running them with ZFS. I think people should be using hardware RAM drives. You can get old Gigabyte i-RAM drives with 4 gig of memory for the cost of a 60 gig SSD, and it will trounce the SSD for speed. I'd put your SSD to L2ARC (cache). -----Original Message----- From: Damien Fleuriot [mailto:ml@my.gd] Sent: Thursday, January 06, 2011 5:20 AM To: Artem Belevich Cc: Chris Forgeron; freebsd-stable@freebsd.org Subject: Re: ZFS - moving from a zraid1 to zraid2 pool with 1.5tb disks You both make good points, thanks for the feedback :) I am more concerned about data protection than performance, so I suppose raidz2 is the best choice I have with such a small scale setup. Now the question that remains is wether or not to use parts of the OS's ssd for zil, cache, or both ? --- Fleuriot Damien On 5 Jan 2011, at 23:12, Artem Belevich <fbsdlist@src.cx> wrote: > On Wed, Jan 5, 2011 at 1:55 PM, Damien Fleuriot <ml@my.gd> wrote: >> 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... > > In second case you get better performance, but lose some data > protection. It's still raidz1 and you can't guarantee functionality in > all cases of two drives failing. If two drives fail in the same vdev, > your entire pool will be gone. Granted, it's better than single-vdev > raidz1, but it's *not* as good as raidz2. > > --Artem
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