I do the same with ACARD… Works well enough. Fred
From: zfs-discuss-boun...@opensolaris.org [mailto:zfs-discuss-boun...@opensolaris.org] On Behalf Of Jason Warr Sent: 星期四, 十二月 30, 2010 8:56 To: zfs-discuss@opensolaris.org Subject: Re: [zfs-discuss] SAS/short stroking vs. SSDs for ZIL HyperDrive5 = ACard ANS9010 I have personally been wanting to try one of these for some time as a ZIL device. On 12/29/2010 06:35 PM, Kevin Walker wrote: You do seem to misunderstand ZIL. ZIL is quite simply write cache and using a short stroked rotating drive is never going to provide a performance increase that is worth talking about and more importantly ZIL was designed to be used with a RAM/Solid State Disk. We use sata2 HyperDrive5 RAM disks in mirrors and they work well and are far cheaper than STEC or other enterprise SSD's and have non of the issue related to trim... Highly recommended... ;-) http://www.hyperossystems.co.uk/ Kevin On 29 December 2010 13:40, Edward Ned Harvey <opensolarisisdeadlongliveopensola...@nedharvey.com<mailto:opensolarisisdeadlongliveopensola...@nedharvey.com>> wrote: > From: Bob Friesenhahn > [mailto:bfrie...@simple.dallas.tx.us<mailto:bfrie...@simple.dallas.tx.us>] > Sent: Tuesday, December 28, 2010 9:23 PM > > > The question of IOPS here is relevant to conversation because of ZIL > > dedicated log. If you have advanced short-stroking to get the write latency > > of a log device down to zero, then it can compete against SSD for purposes > > of a log device, but nobody seems to believe such technology currently > > exists, and it certainly couldn't compete against SSD for random reads. > > (ZIL log is the only situation I know of, where write performance of a drive > > matters and read performance does not matter.) > > It seems that you may be confused. For the ZIL the drive's rotational > latency (based on RPM) is the dominating factor and not the lateral > head seek time on the media. In this case, the "short-stroking" you > are talking about does not help any. The ZIL is already effectively > "short-stroking" since it writes in order. Nope. I'm not confused at all. I'm making a distinction between "short stroking" and "advanced short stroking." Where simple "short stroking" does as you said - eliminates the head seek time but still susceptible to rotational latency. As you said, the ZIL already effectively accomplishes that end result, provided a dedicated spindle disk for log device, but does not do that if your ZIL is on the pool storage. And what I'm calling "advanced short stroking" are techniques that effectively eliminate, or minimize both seek & latency, to zero or near-zero. What I'm calling "advanced short stroking" doesn't exist as far as I know, but is theoretically possible through either special disk hardware or special drivers. _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org<mailto:zfs-discuss@opensolaris.org> http://mail.opensolaris.org/mailman/listinfo/zfs-discuss _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org<mailto:zfs-discuss@opensolaris.org> http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
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