raid5 question(s)

[Homerboy]

If I get a RAID 5 controller, do all the drives have to be IDENTICAL?
I have a smattering of dif 160gig drives... makes, models etc... do they all have to be EXACTLY the same for RAID 5 to work, or do they just have to be the same size?

 

[Markfw]

they work better being identical, but if they are all 160gig (give or take a few bytes) they will be fine. I assume these are IDE drives. I don;t know a good controller for IDE, but I heard that 3ware made some good ones.

 

[Homerboy]

yeah I looked at the 3wave and the promise. The 3wave is nearly 2x expensive...
and its odd to me that the 3wave that supports 4 IDE devices has 4 IDE ports... not 2 (1 master 1 slave on the ribbons?)

 

[Markfw]

Probably since you get more speed out it with only one device per channel. The 133 m/sec PCI bus will be killing your transfer speed though. My SCSI card has the same problem. Now seek times are anoher matter. I get 1ms average seek.

 

[Homerboy]

speed is of a nominal issue for me for this application really. I mean as long as its not a snails pace Ill be fine. This is purely for space and backup of crucial (and non crucial) data

 

[MichaelD]

FWIW, I have a 3Ware 7000-2. It's a two-channel IDE Raid card. Takes two IDE drives. I hooked up two ATA100 drives to it and regularly got 95MB/s reads.

 

[Homerboy]

Originally posted by: MichaelD
FWIW, I have a 3Ware 7000-2. It's a two-channel IDE Raid card. Takes two IDE drives. I hooked up two ATA100 drives to it and regularly got 95MB/s reads.

so I assume then I cant get the 2 channel one that you have and hook up 2x2 IDE ribbons?

 

[Pariah]

No, the higher end ATA RAID cards only allow one drive per channel and come with all the one device ATA cables for each channel. Drives for RAID 5 that are not intended for performance need not be identical, though the same capacity is highly recommended, as you say they are. RAID 5 isn't really designed for incredible performance. Reads should be pretty decent on most hardware RAID 5 controllers, however, except for 3Ware, writes will be painfully slow, in the single digits. For a storage array, slow write speeds shouldn't be much of an issue.

 

[Homerboy]

Originally posted by: Pariah
No, the higher end ATA RAID cards only allow one drive per channel and come with all the one device ATA cables for each channel. Drives for RAID 5 that are not intended for performance need not be identical, though the same capacity is highly recommended, as you say they are. RAID 5 isn't really designed for incredible performance. Reads should be pretty decent on most hardware RAID 5 controllers, however, except for 3Ware, writes will be painfully slow, in the single digits. For a storage array, slow write speeds shouldn't be much of an issue.

whoah whoah whoah... SINGLE digit? This is for a fairly active home file server. I'm running back up of all our crucial files (personal and business), ripped DVDs, CDs, lots of home video, family jpgs etc etc...

If writes are that slow, maybe thats not an option.

 

[Pariah]

If you're transferring the files over a network, you're limited to single digit transfers anyway. For a storage server, write speed should not be of much importance. It may be a nuisance when you first try to transfer everything you have to the system, but after that you shouldn't not be constantly writing to it.

 

[DaCurryman]

How about for an HTPC build where data is coming in from a PVR-250? I was hoping to do a 4x120GB RAID-5 array.

 

[ViRGE]

Originally posted by: Pariah
If you're transferring the files over a network, you're limited to single digit transfers anyway. For a storage server, write speed should not be of much importance. It may be a nuisance when you first try to transfer everything you have to the system, but after that you shouldn't not be constantly writing to it.

Why the single digit write speeds though? I've used more professional RAID arrays(specifically, an Apple XServe RAID), and the writes and reads on that sucker were plenty fast.

 

[Pariah]

Don't know exactly, probably a combination of things. Too weak a processor, no cache, and poor software. Don't see too many retail boxed $250 SCSI RAID 5 cards do you? You get what you pay for.

 

[imported_Nacelle]

I have a Rocket Raid 404. It has four channels. You can have 8 drives hooked to it at the same time. That means 2 on 1 channel though. So, you won't get as much speed. But, it will work. And yes, you can use any size drive you want. It just makes all the drives equal the smallest one. if you had 2-200gb drives and 1-50gb drive. a raid 5 array would equal 100gb.