Date: Thu, 6 Jan 2011 17:42:49 -0800 From: Jeremy Chadwick <freebsd@jdc.parodius.com> To: Jean-Yves Avenard <jyavenard@gmail.com> Cc: "freebsd-stable@freebsd.org" <freebsd-stable@freebsd.org>, Artem Belevich <fbsdlist@src.cx>, Chris Forgeron <cforgeron@acsi.ca> Subject: Re: ZFS - moving from a zraid1 to zraid2 pool with 1.5tb disks Message-ID: <20110107014249.GA3719@icarus.home.lan> In-Reply-To: <AANLkTikfb7XzCfjetZYK016RoRG3JSs-%2BwiaaoCPTG8q@mail.gmail.com> 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> <BEBC15BA440AB24484C067A3A9D38D7E0149F32D33F9@server7.acsi.ca> <AANLkTikfb7XzCfjetZYK016RoRG3JSs-%2BwiaaoCPTG8q@mail.gmail.com>
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On Fri, Jan 07, 2011 at 12:29:17PM +1100, Jean-Yves Avenard wrote: > On 6 January 2011 22:26, Chris Forgeron <cforgeron@acsi.ca> wrote: > > 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). > > Where do you find those though. > > I've looked and looked and all references I could find was that > battery-powered RAM card that Sun used in their test setup, but it's > not publicly available.. DDRdrive: http://www.ddrdrive.com/ http://www.engadget.com/2009/05/05/ddrdrives-ram-based-ssd-is-snappy-costly/ ACard ANS-9010: http://techreport.com/articles.x/16255 GC-RAMDISK (i-RAM) products: http://us.test.giga-byte.com/Products/Storage/Default.aspx Be aware these products are absurdly expensive for what they offer (the cost isn't justified), not to mention in some cases a bottleneck is imposed by use of a SATA-150 interface. I'm also not sure if all of them offer BBU capability. In some respects you might be better off just buying more RAM for your system and making md(4) memory disks that are used by L2ARC (cache). I've mentioned this in the past (specifically "back in the days" when the ARC piece of ZFS on FreeBSD was causing havok, and asked if one could work around the complexity by using L2ARC with md(4) drives instead). I tried this, but couldn't get rc.d/mdconfig2 to do what I wanted on startup WRT the aforementioned. -- | Jeremy Chadwick jdc@parodius.com | | Parodius Networking http://www.parodius.com/ | | UNIX Systems Administrator Mountain View, CA, USA | | Making life hard for others since 1977. PGP 4BD6C0CB |
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