Date: Tue, 28 Aug 2012 16:07:52 -0700 From: Josh Paetzel <josh@tcbug.org> To: Andy Young <ayoung@mosaicarchive.com> Cc: freebsd-hardware@freebsd.org Subject: Re: Support for Fusion IO drives? Message-ID: <503D4F48.9020108@tcbug.org> In-Reply-To: <CAK6u07XeH%2BjTg2M4s%2BpP=-HNgmtNC==Bh4fbZqCVWo5O7_rbyg@mail.gmail.com> References: <CAHMRaQerwM4FRnfkc-1Yaa7JUVjJJazDhhQ_JZzE_Wn5OzKL2Q@mail.gmail.com> <503D3026.6010901@ixsystems.com> <CAK6u07XeH%2BjTg2M4s%2BpP=-HNgmtNC==Bh4fbZqCVWo5O7_rbyg@mail.gmail.com>
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>> -------- Original Message -------- >> Subject: Support for Fusion IO drives? >> Date: Tue, 28 Aug 2012 16:46:00 -0400 >> From: Andy Young <ayoung@mosaicarchive.com> >> To: freebsd-hardware@freebsd.org >> >> >> We are investigating adding SSDs as ZIL devices to boost our ZFS write >> performance. I read an article a while ago about iX Systems teaming up >> with >> Fusion IO to integrate their hardware with FreeBSD. Does anyone know >> anything about supported drivers for Fusion IO's iodrives? >> >> Thanks! >> >> Andy >> _______________________________________________ >> freebsd-hardware@freebsd.org mailing list >> http://lists.freebsd.org/mailman/listinfo/freebsd-hardware >> To unsubscribe, send any mail to >> "freebsd-hardware-unsubscribe@freebsd.org" >> >> >> >> I'll put on my iXsystems hat here, as well as my fast storage, ZFS and Fusion-I/O hat. The ZFS filesystem supports dedicated ZIL devices, which can accelerate certain types of write requests, notably related to fsync. The VMWare NFS client issues a sync with every write, and most databases do as well. In those types of environments having a fast dedicated ZIL device is almost essential. In other environments the benefits of a dedicated ZIL range from non-existent to substantial. A good dedicated ZIL device is all about latency. It doesn't need to be large, in fact it will only ever handle 10 seconds of writes, so 10x network bandwidth is worst case. (In most environments this means 20GB is larger than needed). Fusion-I/O cards are far too large to be cost effective ZIL devices. Even though they do rock at I/O latency, the really fast ones are also fairly large, so the $/GB on them isn't so attractive. There are better options for ZIL devices. Another consideration is the Fusion-I/O driver is fairly memory hungry, which competes with memory ZFS wants to use for read caching. Now as an L2ARC device, that's a whole different can of worms. Command line used: iozone -r 4k -s 96g -i 0 -i 1 -i 2 -t 8 Parent sees throughput for 8 readers = 1712399.95 KB/sec L2 ARC Breakdown: 197.45m Hit Ratio: 98.61% 194.71m L2 ARC Size: (Adaptive) 771.13 GiB ARC Efficiency: 683.40m Actual Hit Ratio: 71.09% 485.82m ~ 800GB test data, all served from cache. If you are considering Fusion-I/O, the FreeBSD driver is generally not released to the general public by Fusion-I/O, but can be obtained from various partners. (I believe iXsystems is the only FreeBSD friendly fusion-i/o partner but could be wrong about that) -- Thanks, Josh Paetzel
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