From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andre Tomt Subject: Re: Low cost PCI-E unRAID - Supermicro AOC-SASLP-MV8 Driver/LBA questions for HW owners/users Date: Sun, 23 Jan 2011 03:44:39 +0100 Message-ID: <4D3B9617.9010800@tomt.net> References: <4D39D8B5.1090901@hardwarefreak.com> <4D3B0009.6020006@hardwarefreak.com> <4D3B6B05.1020303@shiftmail.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <4D3B6B05.1020303@shiftmail.org> Sender: linux-raid-owner@vger.kernel.org To: Michael Evans Cc: Spelic , linux-raid List-Id: linux-raid.ids On 01/23/2011 12:40 AM, Spelic wrote: > On 01/22/2011 09:36 PM, Michael Evans wrote: >> >> Also, you are half right about this being a 'dream' system. For years >> I've been using a carefully selected 6 port motherboard, and 3 PCI-e >> 1x cards to get a total of 12 ports. > > So you are trying to reach 12 ports? > C'mon don't be cheap, there are lightning-fast 16-ports HBA controllers > from LSI, at 6.0gbit/sec, $350 or so. $25 per port is not much; it is > much less than the cost of the disk you are attaching to it. > This frees you from the choice of the mainboard, and this is important, > firstly because you can save $$$ in there, and secondly because if the > mainboard fails, what are you going to do? you are going to buy another > one with 6 ports? Difficult to find... and expensive also. > Also using 2 different controllers for your disks (part from mainboard, > part from addon card) is a bit of pain in the *** for administration > things, also performances would be the slowest of the two for every > request. Since we're talking about "non hardware raid" usage, I don't really understand how it would be harder to manage mixed controllers? Care to explain? I can't quite get the performance statement to compute, either.. Its not like the same I/O goes out to all controllers. If your other controller is slower, just put fewer drives on it. Balance it out. Anyways, If you settle for SATA and a desktop motherboard, most mid to high end s1156/1155 motherboards nowadays are fitted with 6 to 8 SATA ports. They're in now way hard to come by - even 8 ports seems to be available at $130 (I spent 10 seconds looking on newegg). But then again not all of them will *boot* off 3TB drives - at least many of the 1156 ones. As for on board performance, integrated Intel ICH's AHCI controllers tend to top out at around 750MB/s aggregate. 6 ports are usually on the Intel, the rest on some AHCI compatible chip from Marvell. In general you can expect around 1GB/s aggregated from the on board controllers at the same time on a standard socket 1156/1155 desktop class intel chipset based motherboard. Regarding the AOC-SASLP-MV8, yes, they're not worth it - the mvsas driver is still buggy when used with SATA. I have heaps of issues with mine - at least when using Seagate 7200.11 1.5TB drives on 2.6.36.3. Keeps stalling and throwing IO errors (no corruption yet, though). The card also tops out at ~700MB/s aggregate - and we can't have any of that can we ;-) So yeah, the LSI based cards are seems like a good bet if you go the SAS HBA route. Even the previous 3Gb/s generation can do a cool 1600-1700MB/s if you give them 8 pcie lanes. If he ever plan to expand into expander (he he) territory, that bandwidth is good to have. Well, in a "dream system" anyway, any normal workloads are generally more random and much, much lower in throughput. But hey, we're going for bragging rights here, right? :-)