From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andre Tomt Subject: Re: Typical RAID5 transfer speeds Date: Sun, 20 Dec 2009 15:53:08 +0100 Message-ID: <4B2E3A54.5050009@tomt.net> References: <4B2D4731.3090702@gmail.com> <4877c76c0912192021s2c3da63au57f5dcb0391b3eb3@mail.gmail.com> <200912200255.16513.tfjellstrom@shaw.ca> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <200912200255.16513.tfjellstrom@shaw.ca> Sender: linux-raid-owner@vger.kernel.org To: tfjellstrom@shaw.ca Cc: Michael Evans , Roger Heflin , Matt Tehonica , linux-raid@vger.kernel.org List-Id: linux-raid.ids On 20.12.2009 10:55, Thomas Fjellstrom wrote: > While the driver support isn't "perfect"*, I have an AOC-SASLP-MV8, a 2 port > SAS 4x PCI-e card. (with SAS->SATA converters, its an 8 port SATA card) > > When I was running some tests on individual drives, and watching iostat, I > saw over 500MB/s combined throughput, and that was with only 5 drives. > Theoretically it should be capable of 1GB/s given its a x4 card. > Theoretically. > > At the very least, the card should be more than capable of providing enough > bandwidth for all 8 ports to be filled with regular mechanical hard drives > (sans port expanders). Having tried it connected directly to the north bridge, it seems to top out at ~650-700MB/s (also using Windows driver). Which is not too bad for a pcie 1.0 x4 card, but unfortunatly will only manage to saturate about ~5 modern mechanical drives (currently at 120-130MB/s each for SATA 7200rpm), if high sequential performance is all you're looking for. Currently I solved that by having 4 drives from the array on that card, and populating the last four ports with with drives that are seldomly used and when used get mostly random i/o but still needs a port ;-) Still good value for money, indeed.