I've got a tower computer with 6 SATA slots. Is it a worthwhile practice to stripe or RAID your system drive to increase reliability and performance? Are there any technical considerations not to? If I did stripe 500GB drives, should I partition my OS or just keep one 3TB volume? What level of RAID should I use?
RAID system drive
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- Sep 13, 2010
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I would recommend that you not use motherboard controller RAID for your OS drive, it creates another significant reliability issue.
If you want a reliable high performance OS alternative get an SSD and use your 3TB for storage.
If you want a reliable high performance OS alternative get an SSD and use your 3TB for storage.
Thanks, RealBeast. You're saying that if the OS drive is a RAID it creates reliability issues. Like what? The conventional idea is that RAID creates more reliability, or at least a recovery solution if your volume fails.
I was considering an SSD as a boot disk, but thought that the striping of several SATAs would speed up processes similarly. Several 1TB and 500GB drives have become available, and I have these empty slots...
I was considering an SSD as a boot disk, but thought that the striping of several SATAs would speed up processes similarly. Several 1TB and 500GB drives have become available, and I have these empty slots...
- Sep 13, 2010
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I respond to tons of threads dealing with the loss of data on a RAID array based on motherboard controllers. They are inherently less stable than a real RAID controller and even a simple power loss or single BSOD can blow up the array.
You will never approach an SSD with HDDs because of the low access time and high random performance of an SSD. Before SSDs came along I often ran my OS on 2 or 4 10k or 15k rpm drives in RAID 0. Now I would not consider anything but an SSD for my OS. But once you have a single SSD you would not notice any real world improvement in performance over two SSDs in RAID 0 (benchmarks improve but it is not noticeable in real use). Plus you again would add the problem of using a motherboard RAID controller.
I still use a lot of RAID for storage, usually RAID 5 or 6, but using a RAID controller (like an Adaptec 6805 or 7805). That is different than a speed issue though, it's about size. My current home storage array is 8 x 3TB in RAID 6. Large redundant arrays will give you great sequential performance, but that is only helpful for large files -- like streaming BluRay ISO images to HTPCs.
You will never approach an SSD with HDDs because of the low access time and high random performance of an SSD. Before SSDs came along I often ran my OS on 2 or 4 10k or 15k rpm drives in RAID 0. Now I would not consider anything but an SSD for my OS. But once you have a single SSD you would not notice any real world improvement in performance over two SSDs in RAID 0 (benchmarks improve but it is not noticeable in real use). Plus you again would add the problem of using a motherboard RAID controller.
I still use a lot of RAID for storage, usually RAID 5 or 6, but using a RAID controller (like an Adaptec 6805 or 7805). That is different than a speed issue though, it's about size. My current home storage array is 8 x 3TB in RAID 6. Large redundant arrays will give you great sequential performance, but that is only helpful for large files -- like streaming BluRay ISO images to HTPCs.
Thanks again, RealBeast. I'll keep my system drive JBOD, whether it's SATA or SSD. Now, loading up those other internal slots with SATAs and creating a RAID, would that be "based on motherboard controllers?" Or does that caution just apply to OS disks?
- Sep 13, 2010
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Using a motherboard controller still is an issue, but at least all you would lose is your data. You still have your OS and if you backup elsewhere data loss is not really an issue other than array rebuild and data restoration time. Unless you need a large storage array, I would stick with a 2-3TB HDD for storage. You really don't need to use all your SATA connectors. 
"backup elsewhere?" I wasn't planning on it. The RAID was supposed to protect the data...but I guess you're saying that internal RAID that relies on the motherboard controller is the weakest link, more likely to corrupt the RAID and lose all the data than a drive failing and requiring to be rebuilt.
(takes deep bow, jester hat falls off)
I'm not talking about mission critical, "I'd spend $thousands in disk recovery" kind of data; RAID redundancy should be better than just-a-bunch-of-disks, which to me is the dangerous tightrope walk. ("Backup" was your word, not mine!) Especially since these are used disks of indeterminate age (up to three years old?) I'm looking for a safety net that also increases the read/write speed. Isn't that what six internal drive bays is for?
I'm not talking about mission critical, "I'd spend $thousands in disk recovery" kind of data; RAID redundancy should be better than just-a-bunch-of-disks, which to me is the dangerous tightrope walk. ("Backup" was your word, not mine!) Especially since these are used disks of indeterminate age (up to three years old?) I'm looking for a safety net that also increases the read/write speed. Isn't that what six internal drive bays is for?
- Sep 13, 2010
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Nope, not mission critical -- I'm only talking home storage here. There are various levels of data though. You should backup anything that you don't want to lose, that is pretty much the rule. And RAID is not backup, especially not if you are not using a RAID card. It all becomes a question of relative risk v. data value. There are things that are not worth backing up -- like things that you can easily download again. There are things that are worth some level of effort, like a ripped movie and you own the disk but it would take time to rip again, although you probably would consider that optical disk the backup. On the other end there would be things like family pictures that you want that are not duplicated anywhere (like Mom's computer). You would be wise to back that sort of data up to a free cloud site.
My point is that RAID is a bit of a safety net, but it is a net that might fail so treat it that way. It is really primarily a faster and larger storage space that can deal with a single (or even two, in RAID 6) failed drives. I've seen a number of RAID 5 arrays lose a second drive during a rebuild for a first failed drive -- and that eliminates all the data on the entire array with no chance of recovery just due to a single URE (unrecoverable read error) on the second drive.
The empty slots in a case are not a guide to storage needs.
My point is that RAID is a bit of a safety net, but it is a net that might fail so treat it that way. It is really primarily a faster and larger storage space that can deal with a single (or even two, in RAID 6) failed drives. I've seen a number of RAID 5 arrays lose a second drive during a rebuild for a first failed drive -- and that eliminates all the data on the entire array with no chance of recovery just due to a single URE (unrecoverable read error) on the second drive.
The empty slots in a case are not a guide to storage needs.
You've made the distinction of "home storage," which this is, unless I get tempted to edit video with Adobe Premiere, and the conventional wisdom is to not use internal AV storage, I guess to keep it on a separate bus from OS business. You've indicated that RAID could create reliability issues rather than solving them -- is a "home storage" PC better off keeping to JBOD and doing disk-by-disk damage control? Is RAID storage (and recovery) best left to those more IT-savvy than I've revealed myself to be?
- Sep 13, 2010
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RAID is sometimes useful and even necessary, but can put your data at risk if you don't spend the money to get high quality parts to reduce that potential. It can also be a pain to maintain, so I usually advise to use a large drive or two if that will do instead. If you anticipate a large volume of data then it may be worth learning about. For example, if you really wanted a big home server the first question is RAID or maybe a less expensive and very bulletproof OS using FreeNAS with ZFS raidz and drives on a relatively cheap and simple host bus adapter (like an IBM M1015).
- Sep 13, 2010
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An HBA is like a PCIe SATA card, just with more ports -- although unlike a SATA card an HBA usually can do very basic RAID levels but will not do RAID 5 or 6. For that you need a real RAID controller card (around $350 with the cable). It usually sits in the same case as the motherboard and drives, as it is a fairly simple PCIe card.
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