PCIe SATA RAID controllers
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Posted by Calab on August 22, 2008, 12:07 pm
Please log in for more thread options Can anyone suggest some inexpensive PCIe SATA RAID controllers? I have eight drives that I need to build into one four terabyte RAID5 array. Any 8 port card I find is expensive. I know that there are cards that you can install two of and they can cooperate and create a single array, but this is a detail I that isn't given very often. Any suggestions on what I can do? | |||||||||||||
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Posted by Paul on August 22, 2008, 3:51 pm
Please log in for more thread options Calab wrote: One issue I see, is a maximum array size issue. A 32 bit OS tends to use a 32 bit sector number to address the array. That gives a 2.2TB limit for array size. If you want to build a single 4GB array, there would have to be a "trick" to it. Investigate the size limit carefully, before proceeding to build a single 4TB array. It could be this is fixed, with the right OS choice. One user of an Areca card posted a problem about his usage of disks. He said his array was "working", and he copied over some big files, just past the 2.2TB point, and the file system was corrupted. On downloading the Areca manual, it turns out the Areca can support up to 16TB or so. But a special setting must be enabled in the Areca, which he failed to do, in order to address 16TB with a 32 bit sector address. That trick is, to change the effective size of a sector. If this was my array, I would copy fake test data to it, until I got past 2.2TB, then reboot and see if the file system is totally intact. So your first planning activity, would be to investigate whether a 4TB array can be supported without tricks in your environment. Tomshardware had an article years ago, about using softraid built into Windows, to control an array of disks. The idea would be, to use non-RAID cards, connect your eight disks, and then use RAID5 built into Windows. The disk controllers in that case, could be more ordinary ones (say, a couple of SIL3114 based cards). The problem I see there, is what software interface is available for repairing the array. The Tomshardware article didn't explain that part, and merely got the array working with new disks. Other than that, you could use SIL3114 cards, and build two RAID5 arrays. And those cards are pretty cheap. It really all depends on how dependable your implementation has to be. This is an example of a 4 port SIL3114 card from Rosewill. There are a total of six physical ports, of which four can work. A jumper block steers two ports, to either the two front connectors, or to two internal connectors. In normal usage, the ESATA connectors on the faceplate would be disabled, and you'd be using the four internal connectors for disks. http://c1.neweggimages.com/NeweggImage/productimage/16-132-013-11.jpg This is a comment from a reviewer. "Pros: Easy set up, SATA and E-SATA ports. Cons: Parity RAID (RAID 5) will not build correctly, tech support has not responded to any of the support requests sent. Other Thoughts: It's unfortunate that parity RAID constantly fails to build with known good harddisks. Card works well without RAID, E-SATA is handy." So that is part of the fun of a cheap product. The fun begins, after the array fails, and then you discover just how good the firmware and software for the thing really are. I've also heard of cases, where someone owns a cheap RAID5, one disk fails, and rather than being in "degraded" state, the array fails to work at all. Which means for whatever reason, the redundancy feature is not working. RAID5 is supposed to survive a single drive failure. Another way to build an array, is use a card with a SIL3132, which supports port multipliers, and the flash chip on the card can be flashed to use the RAID BIOS. Then connect two five port, port multiplier cards to it. The SIL3132 can control ten disks in a RAID array. You want a card with the right kind of flash chip on it, so it can be flashed to use the RAID BIOS (that is, if the card ships with the BASE BIOS, and needs to be changed to RAID). http://www.newegg.com/Product/Product.aspx?Item=N82E16815124027 The tools for modding the card are here. http://www.siliconimage.com/support/supportsearchresults.aspx?pid=32&cid=15&ctid=2&osid=0& The port multiplier boxes are the tricky part. Shop carefully for a supplier of these. These items take one SATA port and make five ports from it, but they only work when plugged into certain controllers, such as the SIL3132. Your total project cost becomes $20 for the SIL3132, then $100 + $100 to get two port multiplier boxes, for a total of $220 or so plus cables. Check resellerratings.com for the reputation of some of the small companies selling port multipliers. You can see some products here, made by Addonics. http://www.addonics.com/products/pm/ http://www.addonics.com/products/host_controller/ad5sapm-e.asp $85 http://www.addonics.com/products/host_controller/extpm.asp $95 http://www.resellerratings.com/store/Addonics (reviews look typical) (probably not a ripoff) Naturally, using the SIL3132 approach, depends on it having drivers for whatever OS allows >2.2TB arrays. Being a "softraid" without
an XOR engine or DRAM cache, means performance will be "average"
and not outstanding. The reason good cards are expensive, is because they've been designed by serious people, for use in servers. And the company may have more than a casual interest in getting it right. Companies using the SIL3132 chip, just copy the hardware design, and rely on Silicon Image to provide good, working, firmware and software. The companies don't add any value to the product, such as by rewriting the software and adding features. The port multiplier boxes are "dumb", so there is no firmware/software issue with those. But they do have to be plugged to devices that understand how to control them (which is why the SIL3132 RAID Management software for Windows is an important component of the package). HTH, Paul | |||||||||||||
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Posted by Calab on August 24, 2008, 8:59 pm
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> Calab wrote:
>> Can anyone suggest some inexpensive PCIe SATA RAID controllers? I have
>> eight drives that I need to build into one four terabyte RAID5 array. Any >> 8 port card I find is expensive. I know that there are cards that you can >> install two of and they can cooperate and create a single array, but this >> is a detail I that isn't given very often. > One issue I see, is a maximum array size issue. A 32 bit OS tends to use
> a 32 bit sector number to address the array. That gives a 2.2TB limit for > array size. If you want to build a single 4GB array, there would have to > be > a "trick" to it. Investigate the size limit carefully, before proceeding > to build a single 4TB array. It could be this is fixed, with the right > OS choice. OS choice is Windows Standard Server 2003. This SHOULD allow for up to 16TB arrays. Of course the RAID card would also have to support it. Currently we have an Adaptec 21610SA PCIx RAID controller. It has 16 SATA ports on it, but Adaptec says that the card can't build an array larger than 2TB, regardless of OS. > Tomshardware had an article years ago, about using softraid built into
> Windows, to control an array of disks. The idea would be, to use non-RAID > cards, connect your eight disks, and then use RAID5 built into Windows. > The disk controllers in that case, could be more ordinary ones (say, > a couple of SIL3114 based cards). The problem I see there, is what > software interface is available for repairing the array. The Tomshardware > article didn't explain that part, and merely got the array working with > new disks. I believe that I read the same article. It said that arrays could be moved to new Windows systems for rebuilding, if necessary. I was actually running a four drive RAID5 array with the Windows software RAID. Then I found out that you can't add a drive and grow the software array. > Other than that, you could use SIL3114 cards, and build two RAID5 arrays.
> And those cards are pretty cheap. It really all depends on how dependable > your implementation has to be. I could do this. This is actually what it looks like we need to do with the Adaptec card. It can support multple arrays, as long as they aren't larger than 2TB. > Another way to build an array, is use a card with a SIL3132, which
http://www.siliconimage.com/support/supportsearchresults.aspx?pid=32&cid=15&ctid=2&osid=0&
> supports port multipliers, and the flash chip on the card can be > flashed to use the RAID BIOS. Then connect two five port, port > multiplier cards to it. The SIL3132 can control ten disks in a > RAID array. You want a card with the right kind of flash chip on > it, so it can be flashed to use the RAID BIOS (that is, if the > card ships with the BASE BIOS, and needs to be changed to RAID). > > http://www.newegg.com/Product/Product.aspx?Item=N82E16815124027 > > The tools for modding the card are here. > > >
> The port multiplier boxes are the tricky part. Shop carefully > for a supplier of these. These items take one SATA port and make > five ports from it, but they only work when plugged into certain > controllers, such as the SIL3132. Your total project cost becomes > $20 for the SIL3132, then $100 + $100 to get two port multiplier > boxes, for a total of $220 or so plus cables. Check resellerratings.com > for the reputation of some of the small companies selling port > multipliers. Very cool. I did not know about the multipliers. This will be something to take into consideration. > Naturally, using the SIL3132 approach, depends on it having drivers
> for whatever OS allows >2.2TB arrays. Being a "softraid" without > an XOR engine or DRAM cache, means performance will be "average" > and not outstanding. Performance is not critical. Most important are the RAID5 abilities, ability to grow the arrays, largest array sizes... in that order. I appreciate the in depth reply. Thank you VERY much! | |||||||||||||
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> drives that I need to build into one four terabyte RAID5 array. Any 8 port
> card I find is expensive. I know that there are cards that you can install
> two of and they can cooperate and create a single array, but this is a
> detail I that isn't given very often.
>
> Any suggestions on what I can do?