I was wondering if anyone had a good resource, preferably online, for RAID 0/1 configurations. I’ve never put together a RAID set before so I really need a start to finish step by step.
Thanks
JonGri
I’m the disk guy here at the office so I can probably address your questions.
Unclear from you question is if you’re looking for advice related to a Raid 0, or a Raid 1, or the more complicated Raid 10, which is both protocols together.
Simply Raid-0 is striping. Blocks of data are broken into pieces as they head to the raid set. Each piece is then written to an individual drive. This is a speed technique and provides no protection in the event of disk failure. As a speed technique it works best when both disks are on different busses, otherwise you just have to serialize down a single bus. If the disk has a large onboard cache, then you might still see some performance gains for same-bus drives but not as significant as for drives on different busses.
RAID-1 is mirrored data. Each block of data heading for a raid-set is duplicated, then each block is written to an individual drive. This provides no performance gains for writes but may provide a small performance gain for reading from the set (but only if the controller supports some form of “read from most available disk” logic). Raid-1 is all about providing protection in the event of disk failure. Again - best performance has the disks on different busses.
Raid 10 (that’s “one, zero”, not “ten”) is a combination of the two. You’ll need a minimum of four disks to pull it off. This could either be a “stripe set of mirrors” or a “mirror set of stripes” depending on whether you stripe then mirror or the reverse. From a performance point of view they’re about the same.
Always plan for controller as well as disk failure. Make sure you mirror between controllers. If you lose a controller, you want to be able to access both stripe columns on the other controller.
[url=http://www.finitesystems.com/PRODUCT/raid/raidlevel.htm]Promise technologies has some nice hardware-based RAID controller cards. You can also implement RAID with using many different kinds of volume management software. Just a warning, if you decide you’re going to do RAID-5, do it with hardware. Soft RAID-5 will eat your CPU’s.
HTH - B
Sorry, correct link: Promise Technology
A number of newer motherboards have RAID controllers built in. If you plan to use this, I suggest:
[ul][li]Don’t use striping on your “primary” drive, the one on which your boot files are stored. Leave it as an unRAIDed "single or as part of a RAID 1.[/li][li]If you’re setting up a new computer, shop around for an extra-large case. Those extra drives take up lots of space.[/li][/ul]
I would second the recommendation of a hardware controller board. You can RAID many plain (and cheap!) IDE ATA drives with one easily. I had (hmm. Have. Need to sell it) an old Poweredge server with 3 SCSI drives on an Adaptec controller. It made RAID the easiest thing in the world, with no software drivers required.
A true hardware RAID card is vast overkill for most users. As long as you’re not running a server or other application where low CPU usage is extremely important, a normal “WinRAID” card the likes of which come on many motherboards will more than suffice, especially given that they’re less then half the price. Highpoint makes some of the best of these, with Promise and Silicon Image also offering consumer-level RAID cards. If you do need a real full hardware RAID card, 3Ware and Adaptec are generally considered good, as well as Promise’s pro-level cards.
Thanks for the advice and tips. I just bought a board with SATA and a built in RAID 0/1 (that’s how it’s listed in the specs) controller. I would be using a mirrored set between two 120 gig drives. I don’t need to do this for any practical reason, mind you, I just want to mess around with it.
Thanks
jongri
I have a 0 RAID myself, with two older 40gig drives.
I use it for video editing. Those capture files are humongous.