Date: Sun, 09 Jan 2011 18:06:58 -0400 From: Chris Forgeron <cforgeron@acsi.ca> To: "freebsd-stable@freebsd.org" <freebsd-stable@freebsd.org> Subject: RE: ZFS - moving from a zraid1 to zraid2 pool with 1.5tb disks Message-ID: <BEBC15BA440AB24484C067A3A9D38D7E0149F32D342A@server7.acsi.ca> In-Reply-To: <AANLkTikaz523zMxKzKe%2BMUoxeS4p=X2Vt0Sm6X_%2BKCsV@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> <20110107014249.GA3719@icarus.home.lan> <AANLkTikaz523zMxKzKe%2BMUoxeS4p=X2Vt0Sm6X_%2BKCsV@mail.gmail.com>
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>> 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 a= bout 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 R= AM drives. You can get old Gigabyte i-RAM drives with 4 gig of memory for t= he cost of a 60 gig SSD, and it will trounce the SSD for speed. >> > (I'm making an updated comment on my previous comment. Sorry for the topic = drift, but I think this is important to consider) I decided to do some tests between my Gigabyte i-RAM and OCZ Vertex 2 SSD. = I've found that they are both very similar for Random 4K-aligned Write spee= d (I was receiving around 17,000 IOPS on both, slightly faster ms access ti= me for the i-RAM). Now, if you're talking 512b aligned writes (which is wha= t ZFS is unless you've tweaked the ashift value) you're going to win with a= n i-RAM device. The OCZ Drops down to ~6000 IOPS for 512b random writes. Please note, that's on a used Vertex 2. A fresh Vertex 2 was giving me 28,0= 00 IOPS on 4k aligned writes - Faster than the i-RAM. But with more time, i= t will be slower than the i-RAM due to SSD fade.=20 I'm seriously considering trading in my ZIL SSD's for i-RAM devices, they a= re around the same price if you can still find them, and they won't degrade= like an SSD does. ZIL doesn't need much storage space. I think 12 gig (3 I= -RAM's) would do nicely, and would give me an aggregate IOPS close to a ddr= drive for under $500.=20 I did some testing with SSD Fade recently, here's the link to my blog on it= if anyone cares for more detail - http://christopher-technicalmusings.blog= spot.com/2011/01/ssd-fade-its-real-and-why-you-may-not.html I'm still using SSDs for my ZIL, but I think I'll be switching over to some= sort of RAM device shortly. I wish the i-RAM in 3.5" format had proper SAT= A power connectors on the back so it could plug into my SAS backplane like = the OCZ 3.5" SSDs do. As it stands, I'd have to rig something, as my SAN he= ad doesn't have any PCI controller slots for the other i-RAM format. -----Original Message----- From: owner-freebsd-stable@freebsd.org [mailto:owner-freebsd-stable@freebsd= .org] On Behalf Of Markiyan Kushnir Sent: Friday, January 07, 2011 8:10 AM To: Jeremy Chadwick Cc: Chris Forgeron; freebsd-stable@freebsd.org; Artem Belevich; Jean-Yves A= venard Subject: Re: ZFS - moving from a zraid1 to zraid2 pool with 1.5tb disks 2011/1/7 Jeremy Chadwick <freebsd@jdc.parodius.com>: > 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 a= bout 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 R= AM drives. You can get old Gigabyte i-RAM drives with 4 gig of memory for t= he 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: > =A0http://www.ddrdrive.com/ > =A0http://www.engadget.com/2009/05/05/ddrdrives-ram-based-ssd-is-snappy-c= ostly/ > > ACard ANS-9010: > =A0http://techreport.com/articles.x/16255 > > GC-RAMDISK (i-RAM) products: > =A0http://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. =A0I'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). > Once you have got extra RAM, why not just reserve it directly to ARC (via vm.kmem_size[_max] and vfs.zfs.arc_max)? Markiyan. > I tried this, but couldn't get rc.d/mdconfig2 to do what I wanted on > startup WRT the aforementioned. > > -- > | Jeremy Chadwick =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0= =A0 =A0 =A0 jdc@parodius.com | > | Parodius Networking =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 http://= www.parodius.com/ | > | UNIX Systems Administrator =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0Mountain = View, CA, USA | > | Making life hard for others since 1977. =A0 =A0 =A0 =A0 =A0 =A0 =A0 PGP= 4BD6C0CB | > > _______________________________________________ > freebsd-stable@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-stable > To unsubscribe, send any mail to "freebsd-stable-unsubscribe@freebsd.org" > _______________________________________________ freebsd-stable@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-stable To unsubscribe, send any mail to "freebsd-stable-unsubscribe@freebsd.org"
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