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I'm looking for a hardware RAID controller. I want something that:

  • Can support 8 or maybe 16 hard drives
  • Won't randomly break, lose my data, etc.

Does anyone have recommendations? It seems like people have reliability issues with RAID controllers.

EDIT:

This would be for a desktop machine acting as a read-intensive database server. The drives are fairly inexpensive ~160GB drives. It is running CentOS.

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Desktop or server? What will the machine be doing? Which OS? What sort of drives? –  Andrew Jun 25 '10 at 5:59
    
This question seems to have degraded into linux software raid evangelism. For simple raid 0 with a couple of disks it can be fine but when you add more disks or use higher raid levels there are further issues to consider. More importantly that is not what the questions asks. –  JamesRyan Jun 25 '10 at 10:57
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your going to stick those 8-16 drives in a cheap external enclosure correct? If so I'll bet that it will cause more problems then the hw raid contoller. –  tony roth Jun 25 '10 at 15:02
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8 Answers

As a sysadmin I have many raid setups using 3ware, LSI and adaptec and they've been fast and reliable. I have had many drive failures and only 1 problem with a controller card ever. If you stick to the flagship models of these proven brands then you can't go wrong.

I think most of the myth is from people trying to use onboard raid which is provided on their motherboards although this is not a true hardware solution.

One of the main advantages of proper hardware raid is that the cache memory has a battery backup. If you run software RAID on a machine without a UPS you are very susceptible to corruption with power outages.

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Agreed - onboard RAID smells :) –  Chopper3 Jun 25 '10 at 11:53
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+1, Main advantages of hardware RAID: Battery Backed Write Cache & Hardware XOR Engine(s). –  Chris S Jun 25 '10 at 12:45
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I know and trust HP's mid-to-top-end controllers but that's when used in HP servers with HP disks, if I had to build from off-the-shelf parts I'd have no hesitation using Adaptec controllers.

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+1, I only use HP or Adaptec cards these days. I really can't say enough good things about them. I've never had any problems using them on SAS or cheap SATA drives (I know certain drives may have compatibility issues, but I haven't encountered any). –  Chris S Jun 25 '10 at 12:44
    
Thanks Chris, I'll be honest I have very little experience of SATA other than my laptops, but I love their SAS stuff and would even use it for my personal kit. –  Chopper3 Jun 25 '10 at 13:25
    
Just stay away from the HP Smart Array E200 controller. I haven't used the higher end controllers, but this one has pretty bad problems with write performance. –  Nic Jan 25 '11 at 0:03
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Software RAID is poo on Windows but works well on Linux. For a linux machine, software RAID is a viable option (although it's not something I'd recommend on Windows).

Pros and Cons of SW RAID

Pros of SW RAID:

  • Cheaper, although a SATA RAID controller might not be much more expensive than a good 8 port SATA card.

  • Portable across different models of host adaptor.

Cons of SW RAID:

  • No BBWC - A cache battery on a HW RAID controller mitigates some risks associated with loss of power.

  • SW RAID volumes (at least the last time I looked) don't support direct mapped I/O. If you're using software that supports this you might get some benefit from a H/W RAID controller with a device driver that supports Direct mapped I/O. This may or may not be an issue.

Hardware RAID in more depth

If you want to do hardware RAID, you're far better getting an older model controller by a better manufacturer (Adaptec, LSI, 3Ware, ICP-Vortex or Intel) than a cheap one. 3Ware, in particular have been making SATA RAId controllers for quite a while and are pretty well established in that space. Typically you can purchase this sort of kit off ebay for a few hundred dollars.

Check the manufacturer's web sites (support, driver downloads will have items for older controllers) and find one with the appropriate specification and bus interface (i.e. don't buy a PCI-X 133 controller for a motherboard with a PCIe x4 slot). Then, go hunting for that model on ebay. Stick to very mainstream types, and you are very unlikely to have issues with getting a replacement controller. Get a battery backup unit for it as well - again, these are often quite cheap on ebay, especially for Adaptec or LSI models.

Note also, that most desktop motherboards don't have PCIe x4 slots, so you will want a machine with a motherboard that does. Asus and various other outfits do make single socket 'workstation' motherboards that have wider slots. Supermicro and Tyan also make a range of two socket motherboards if you need lots of CPU speed or RAM.

One point to note is that RAID metadata formats tend to be fairly consistent within a single manufacturer. Find a range where future versions of the controller will mount arrays from older ones. Most of the major brands of controllers will do this.

I've been using workstations with H/W RAID for database development work for a few years now, and with BBUs on the controllers I have never lost any data. Most of my systems have Adaptec ASR-2200S controllers on them. These seem to be fairly good controllers and the BIOS and disk management facilities are pretty good. If you're doing database work, format the volumes you're putting the database on with a large stripe size, the largest that will fit on a single track of your disks. On a modern-ish SATA drive this will probably be 256K or 512K. Make sure your disk volume allocation units are aligned with the physical stripes on the disk, although this is mostly a NTFS/SQL Server issue - YMMV.

Note that the ASR-2200S is a U320 SCSI controller so you won't be able to use that particular model, but Adaptec make SATA RAID controllers as well, and they all share pretty much the same firmware.

The ASR-2200S will occasionally spuriously take a disk off line if it reports SMART errors. Often you can bring the machine down and remount the disk (unless it really has gone on the fritz) and it will rebuild the array in the background. If you have hot-swappable disks, get a spare disk and tray and just swap the disks out if the controller does this.

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+1 on your Hardware RAID in depth; I agree - better to get an older reliable controller vs. a cheaper/newer one –  osij2is Jun 25 '10 at 14:57
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Your number one biggest problem comes when the RAID controller fails, and you simply can't get a replacement because the model is too old and the manufacturer either won't support an upgrade or has been acquired or gone out of business. Or the system that the card is in fails, and all newer systems won't support your old RAID card because technology has marched on (ISA/PCI/PCIe/etc).

This has happened to me way too many times - it's software RAID for me from now on. The slowdown is completely insignificant with today's CPUs.

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Interesting--I've been reading positive things about software RAID actually. Do you use a SATA controller card? Any recommendations? –  Sam Lee Jun 25 '10 at 6:40
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Seeing as you need to take backups anyway because RAID is not a backup, replacing a controller card once in a blue moon is not that big of a deal. In addition to the speed there are several cases that software raid does not cover but hardware raid does. –  JamesRyan Jun 25 '10 at 9:20
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@Teddy - your claim is not strictly true. Lines of RAID controllers often maintain backward compatibility of array metadata with previous models, allowing you to migrate arrays to a newer machine without having to reformat them. Pretty much any of the major brands like Adaptec, HP, or LSI will do this. See serverfault.com/questions/153605/… for a more in depth discussion of this. Moral of the story: better off buying an older Adaptec or LSI card off Ebay than a new one of a cheap model. –  ConcernedOfTunbridgeWells Jun 25 '10 at 10:40
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Btw if you think that the slowdown is insignificant I advise you to compare the bandwith of your harddrives and the bus that your sata controller is on. Consider that RAID needs to write to multiple simultaneous drives. This is why software RAID is becoming LESS effective with modern systems in comparison to hardware RAID. –  JamesRyan Jun 25 '10 at 10:59
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@Javier - Yes, it does, in a manner of speaking. You can write a single block to the cache, and this is the only traffic that goes over the PCI bus. The controller can then get the old block and parity block off the disk, re-calculate the parity and write the modified data and parity blocks back out to the disk. None of this traffic goes over the PCI bus. –  ConcernedOfTunbridgeWells Jun 25 '10 at 15:50
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I'm using 3Ware (9650), Areca (1230, 1680) and Adaptec (52445) RAID adapters. All work fine, though the Adaptec firmware may not be yet perfect. Areca and 3Ware are sure choice. Areca is supposedly better at small IOs, so should be better for a database server (though in my latest tests there wasn't any meaningful difference).

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The very first RAID card I used was a DEC Storageworks unit. It failed once, but we had no problem restoring the configuration to a replacement card.

Since then, I've only used 2 brands: HP and 3Ware. Both have been extremely reliable. In about 10 years of using Compaq/HP Smartarray controllers, we've never had one fail. We've only used a couple of 3ware controllers, but neither of those has failed.

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I recently acquired an LSI 9261-8i, and am quite pleased.

The administration gui and documentation are equally impressive. Performing firmware upgrades is simple and quick using the CLI.

These new controllers have the SFF (small form factor) cables. Each group of four SATA/SAS cables has a single connector on the controller. These are custom cables, and you probably should get the "kit" that includes the cables. There are also "forward" and "reverse" flavors of these cables, so if you acquire a less expensive generic variety, ensure you understand what you need.

The cache can be configured for write-back without a battery. The battery is rather expensive - $170.

Performance on 8k - 64k block sizes with a consumer device such as this will never be anything close to what can be obtained with an HP P4xx, but is quite respectable on the larger block sizes.

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I would strongly recommend Areca cards. I used to use LSI.

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