Aces High Bulletin Board
General Forums => Hardware and Software => Topic started by: Krusty on May 29, 2009, 11:18:52 PM
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While I can't afford a new system yet, I'm trying to keep an eye on the next system I would build.
I have a question RE: RAID.
Does every SATA drive on a system have to be part of the RAID? I'm seeing more CD-ROM drives in SATA format, so that was part of the question (if 4 HDs and 1 optical would screw things up), but was also wondering if I got a 10000 rpm velociraptor drive to boot off of, but then a normal RAID (I like the error recovery aspect of mirrored RAID) of 3-5 drives.
Can you do that? Or will it try to put the velociraptor into the RAID? I really haven't got into any RAID work so far, am only planning on using BIOS-supported RAID features, and I know these vary from mobo to mobo, so general answers are welcome.
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I'm running a raid on my gigabyte mobo. As far as I know, you can pick and choose which drives you want to be part of the raid.
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Don't focus on recovery that's not really important , at least a lot less important than a good backup.
As an example and an horror story I've been victim (at work) of a disk failure and another during the rebuild :p
I was happy to have a good backup system !
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SATA should not be synonymous with raid. When setting up RAID, you assign which drives are to make up the array. I have 4 SATA drives. 2x250gb in RAID 0, 1x500gb not in the array and an SATA DVD-RW drive.
RAID can be really nice for either speed or backup. But do not make it your only source of backup.
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Sata drives can be used straight up, as is, no raid.
Doesn't matter if they are Hard drive or DVD.
If you have 6 ports you can plug in 6.
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I have one of the better cards (3ware 9650SE) driving eight velociraptors in two distinct RAID0 setups of four drives each. Before going to this setup I tried three distinct two drive setups while also having two drives as separate drives (JBODs). I dont know if a motherboard RAID can do that in all cases but the ones I have owned could.
By the way and just in case you need to know a standard run of the mill PCI RAID card is no better then a motherboard RAID. Velociraptors dont really help a RAID setup until you get off the MB controller.
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I was thinking of the velociraptor for the OS, booting speeds, and some applications (games maybe?), but the price per GB is high, so naturally I'm thinking of something a tier down from "velociraptor" for most of my storage needs.
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Remember also that raid-0 doubles your chances for a catastrophic hardware failure which makes the entire storage media corrupt.
Daily backups are basically a requirement when using Raid-0 and even then you risk losing a days worth of work.
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Krusty unless you are using a highend RAID controller card the 32 meg cache HDs will give you very nearly the same performance in RAID. If you use the drive in a single drive setup the velociraptor will be faster but not anything like RAID fast. The speed advantage a velociraptor has will barely make a difference in boot times.
If you do go to a setup similar to mine I would suggest you use 32 meg cache HDs for quick restore imaging (something like trueimage) just to be on the safe side.
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As the others have said, you should be able to set up whatever raid volumes you want, or leave some drives in and some out. Obviously your motherboard's raid chip could be different, but I doubt it.
Funny but not so funny story: This past weekend, the day before Memorial Day, my boot hard drive failed. It was a 150GB WD Raptor. My other two volumes were both Raid 0s with two drives each. I was careful to keep things I cared about on the two Raid 0 volumes backed up, because they have twice the risk... not so on the boot drive. And of course the boot drive failed and the ones I regularly backed up did not. The lesson I already knew but had to learn again is to backup everything that matters, even if its less at risk.
When I reinstalled I made my boot partition a Raid 1 this time. Too much of a PITA to reinstall everything again. Now I need to see about that Raptor warranty....
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Does every SATA drive on a system have to be part of the RAID?
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No.
Also, most - but not all - RAID controllers will let you run two or more arrays at once. For example, you might be able to run two hard drives in a RAID1 (mirrored) array for a boot partition, plus another three hard drives in a RAID5 (striped with parity) array for a data partition.
Personally, I looked long and hard at RAID for my next build, but I think I'll probably keep it simple: one Raptor for the O/S and swap, one Raptor for data and programs, and a couple of cheap, slow drives for regularly-scheduled image backups via "casper".
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Thanks for all the input, folks. In my original post when I said mirrored, I meant RAID1 (or also considering RAID5), so that any single lost HD can be replaced with no loss of data.
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Thanks for all the input, folks. In my original post when I said mirrored, I meant RAID1 (or also considering RAID5), so that any single lost HD can be replaced with no loss of data.
Just remember that the motherboard built-in raid systems suck totally. Get an add-on card with it's own processor if you want to do raid.
The built in raid chips create a massive problem if your computer should break one day and you want to move the array to an another computer for example..
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Just remember that the motherboard built-in raid systems suck totally. Get an add-on card with it's own processor if you want to do raid.
The built in raid chips create a massive problem if your computer should break one day and you want to move the array to an another computer for example..
Word! :aok
By way of a counter-example: at work I recently had an older, but heavily-used HP DL530 machine go down due to a bad RAID controller (SmartArray 5300). Popped in another controller that was in a machine we don't use much, and presto: machine #1 is up and running again.
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unless you are using a highend RAID controller card the 32 meg cache HDs will give you very nearly the same performance in RAID.
In any configuration that you are likely to use in a desktop system (0, 5 or 10) the advantage of incorporating RAID into the build isn't performance, it's that the system can (far more often) survive a single drive failure and still continue to run.
As has been stated earlier, do NOT use RAID 1, at least with on-board RAID controllers - while in theory it's a wonderful idea for improving performance, in practice (again, using desktop raid controllers - highend cards like the Adaptec are a different animal), you trade twice the likelihood of failure for a marginal at best and usually no increase in performance.
And backups are still just as important - in practice, RAID doesn't guarantee that a drive failure won't put you up to your buttocks in reptiles - more than a few times I've had one drive "die" in such a way that the mirror/array becomes corrupted as a result. But 9 out of 10 times you'll stay running if a drive fails, giving you time to deal with it at your leisure - which is far better than the 10 out of 10 times you'd need to rebuild/restore before you could use the system otherwise.
And I agree, using an add-on controller (while usually a significant expense) can pay for itself in spades - but remember - if you have a spare motherboard or spare computer with a motherboard of the same type, it "counts". This is actually my preference for my personal systems - it's usually cheaper and a wonderful tool for troubleshooting. You'd be surprised how many "quirks" folks blame on software and/or hardware incompatibilities are really just a goobered up piece of hardware - and how often this hardware is on the motherboard. But investing in a good add-on controller gives you freedom to bring up the drive array on a wide range of different hardware, so you'll need to decide which advantage is more important to you - or if neither is worth the additional expense.
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