Thread: RAID Controllers
I'm buying a bunch of new machines (all will run an application that heavily writes to PG). These machines will have 2 spindle groups in a RAID-1 config. Drives will be either 15K SAS, or 10K SATA (I haven't decided if it is better to buy the faster drives, or drives that are identical to the ones we are already running in our production servers, thus achieving commonality in spares across all machines). Controller choice looks to be between Adaptec 6405, with the supercapacitor unit; or LSI 9260-4i with its BBU. Price is roughly the same. Would be grateful for any thoughts on this choice. Thanks.
On Mon, Aug 22, 2011 at 8:42 PM, David Boreham <david_list@boreham.org> wrote: > > I'm buying a bunch of new machines (all will run an application that heavily > writes to PG). These machines will have 2 spindle groups in a RAID-1 config. > Drives will be either 15K SAS, or 10K SATA (I haven't decided if it is > better > to buy the faster drives, or drives that are identical to the ones we are > already running in our production servers, thus achieving commonality in > spares across all machines). > > Controller choice looks to be between Adaptec 6405, with the supercapacitor > unit; > or LSI 9260-4i with its BBU. Price is roughly the same. > > Would be grateful for any thoughts on this choice. If you're running linux and thus stuck with the command line on the LSI, I'd recommend anything else. MegaRAID is the hardest RAID control software to use I've ever seen. If you can spring for the money, get the Areca 1680: http://www.newegg.com/Product/Product.aspx?Item=N82E16816151023 Be sure and get the battery unit for it. You can configure it from an external ethernet connector very easily, and the performance is outstandingly good.
On 8/22/2011 9:42 PM, David Boreham wrote: > I'm buying a bunch of new machines (all will run an application that heavily > writes to PG). These machines will have 2 spindle groups in a RAID-1 config. > Drives will be either 15K SAS, or 10K SATA (I haven't decided if it is > better > to buy the faster drives, or drives that are identical to the ones we are > already running in our production servers, thus achieving commonality in > spares across all machines). > > Controller choice looks to be between Adaptec 6405, with the > supercapacitor unit; > or LSI 9260-4i with its BBU. Price is roughly the same. > > Would be grateful for any thoughts on this choice. I'm by no means an expert but it seems to me if you're going to choose between two 6 GB/s cards you may as well put SAS2 drives in. I have two Adaptec 6445 cards in one of my boxes and several other Adaptec series 5 controllers in others. They suit my needs and I haven't had any problems with them. I think it has been mentioned previously but they do tend to run hot so plenty of airflow would be good. Bob
On 8/23/2011 5:14 AM, Robert Schnabel wrote: > > I'm by no means an expert but it seems to me if you're going to choose > between two 6 GB/s cards you may as well put SAS2 drives in. I have > two Adaptec 6445 cards in one of my boxes and several other Adaptec > series 5 controllers in others. They suit my needs and I haven't had > any problems with them. I think it has been mentioned previously but > they do tend to run hot so plenty of airflow would be good. Thanks. Good point about airflow. By SAS I meant 6Gbit SAS drives. But we have many servers already with 10k raptors and it is tempting to use those since we would be able to use a common pool of spare drives across all servers. 15K rpm is tempting though. I'm not sure if the DB transaction commit rate scales up linearly when BBU is used (it would without BBU).
On August 22, 2011 09:55:33 PM Scott Marlowe wrote: > > If you're running linux and thus stuck with the command line on the > LSI, I'd recommend anything else. MegaRAID is the hardest RAID > control software to use I've ever seen. If you can spring for the > money, get the Areca 1680: > http://www.newegg.com/Product/Product.aspx?Item=N82E16816151023 Be > sure and get the battery unit for it. You can configure it from an > external ethernet connector very easily, and the performance is > outstandingly good. I second the Areca recommendation - excellent controllers. The 1880s are even better.
On 8/22/2011 10:55 PM, Scott Marlowe wrote: > If you're running linux and thus stuck with the command line on the > LSI, I'd recommend anything else. MegaRAID is the hardest RAID > control software to use I've ever seen. If you can spring for the > money, get the Areca 1680: > http://www.newegg.com/Product/Product.aspx?Item=N82E16816151023 Be > sure and get the battery unit for it. You can configure it from an > external ethernet connector very easily, and the performance is > outstandingly good. Thanks. I took a look at Areca. The fan on the controller board is a big warning signal for me (those fans are in my experience the single most unreliable component ever used in computers). Can you say a bit more about the likely problems with the CLI ? I'm thinking that I configure the card once, and copy the config to all the other boxes, so even if it's as obscure as Cisco IOS, how bad can it be ? Is the concern more with things like a rebuild; monitoring for drive failures -- that kind of constant management task ? How about Adaptec on Linux ? The supercapacitor and NAND flash idea looks like a good one, provided the firmware doesn't have bugs (true with any write back controller though).
On Tue, Aug 23, 2011 at 4:42 PM, David Boreham <david_list@boreham.org> wrote: > On 8/22/2011 10:55 PM, Scott Marlowe wrote: >> >> If you're running linux and thus stuck with the command line on the >> LSI, I'd recommend anything else. MegaRAID is the hardest RAID >> control software to use I've ever seen. If you can spring for the >> money, get the Areca 1680: >> http://www.newegg.com/Product/Product.aspx?Item=N82E16816151023 Be >> sure and get the battery unit for it. You can configure it from an >> external ethernet connector very easily, and the performance is >> outstandingly good. > > Thanks. I took a look at Areca. The fan on the controller board is a big > warning signal for me (those fans are in my experience the single most > unreliable component ever used in computers). I've been using Arecas for years. A dozen or more. Zero fan failures. 1 bad card, it came bad. > Can you say a bit more about the likely problems with the CLI ? The MegaCLI interface is the single most difficult user interface I've ever used. Non-obvious and difficult syntax, google it. You'll get plenty of hits. > I'm thinking that I configure the card once, and copy the config > to all the other boxes, so even if it's as obscure as Cisco IOS, I've dealt with IOS and it's super easy to work with compared to MegaCLI. > how bad can it be ? Is the concern more with things like a rebuild; > monitoring for drive failures -- that kind of constant management > task ? All of it. I've used it before just enough to never want to touch it again. There's a cheat sheet here: http://tools.rapidsoft.de/perc/perc-cheat-sheet.html > How about Adaptec on Linux ? The supercapacitor and NAND > flash idea looks like a good one, provided the firmware doesn't > have bugs (true with any write back controller though). I haven't used the newer cards. Older ones had a bad rep for performance but apparently their newer ones can be pretty darned good.
On 08/23/2011 06:42 PM, David Boreham wrote: > I took a look at Areca. The fan on the controller board is a big > warning signal for me (those fans are in my experience the single most > unreliable component ever used in computers). I have one of their really early/cheap models here, purchased in early 2007 . The fan on it just died last month. Since this is my home system, I just got a replacement at Radio Shack and spliced the right connector onto it; had it been a production server I would have bought a spare fan with the system. To put this into perspective, that system is on its 3rd power supply, and has gone through at least 4 drive failures since installation. > Can you say a bit more about the likely problems with the CLI ? Let's see...this week I needed to figure out how to turn off the individual drive caches on a LSI system, they are set at the factory to "use disk's default" which is really strange--leaves me not even sure what state that is. The magic incantation for that one was: MegaCli -LDSetProp DisDskCache -LALL -aALL There's a certainly a learning curve there. > I'm thinking that I configure the card once, and copy the config > to all the other boxes, so even if it's as obscure as Cisco IOS, > how bad can it be ? Is the concern more with things like a rebuild; > monitoring for drive failures -- that kind of constant management > task ? You can't just copy the configurations around. All you have are these low-level things that fix individual settings. To get the same configuration on multiple systems, you need to script all of the changes, and hope that all of the systems ship with the same defaults. What I do is dump the entire configuration and review that carefully for each deployment. It helps to have a checklist and patience. > How about Adaptec on Linux ? The supercapacitor and NAND > flash idea looks like a good one, provided the firmware doesn't > have bugs (true with any write back controller though). I only have one server with a recent Adaptec controller, a 5405. That seemed to be the generation of cards where Adaptec got their act together on Linux again, they benchmarked well in reviews and the drivers seem reasonable. It's worked fine for the small server it's deployed in. I haven't been able to test a larger array with one of them yet, but it sounds like you're not planning to run one of those anyway. If I had 24 drives to connect, I'd prefer an LSI controller just because I know those scale fine to that level; I'm not sure how well Adaptec does there. Haven't found anyone brave enough to try that test yet. -- Greg Smith 2ndQuadrant US greg@2ndQuadrant.com Baltimore, MD PostgreSQL Training, Services, and 24x7 Support www.2ndQuadrant.us