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[OT] RAID questions
I had a 2 drive RAID with 2 IBM Desktar 80GB 7200 rpm 8MB cache drives.
I planned to replace them with 2 Maxtor Diamond Max 10 250GB 7200 rpm 16MB cache drives.
problem is the retailer sent me one 250GB and one 300GB drives.
I went ahead and RAID’d them using Apple Disk utility anyway. It seems to have worked.
Question 1: Can I RAID drives of two different sizes reliably with no performance issues? I am ok with loosing some disk space in the RAID process.
Problem: Before I removed my old RAID I used XBench and did a benchmark on the RAID.
When I installed the new RAID I benchmarked that, and the Read rate was SLOWER on the new Maxtor RAID.
Keep in mind, the old RAID was 2/3 full and the new RAID was empty.Why is this? Both sets of drives are 7200 rpm IDE drives, both had jumpers set to cable select. The newer Maxtor drives have larger 16MB cache, shouldn’t this make them FASTER?
I am running Mac OSX 10.3.9 on my Dual 1ghz PowerMac using the on board IDE cables (no card)
any answers, help or advice would really, really be appreciated. Thanks!
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5 Replies
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Guy,
I hate to be the tider of bad news, but…
First, you got the wrong drives. The Diamondmax drives are just consumer level crap, with just a one year warranty. You should have bought their Maxline III “enterpise level” drives, which cost no more, and have a 5-year warranty. I’ve written several posts about them here. Newegg.com sells the 300gb drives for $130 and the 250gb drives for $99.
Second, striping two different sized drives together creates issues in most cases. Its possible that erasing you drives again in Disk Utility and restripping may rectify the issue and get you up to speed, but probably not.
Again, I’m sorry to deliver bad news, but you deserve to get value for your money.
DRW
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no, thanks for the honesty. This is all kinda temporary until I get a “real” RAID. Just need some quick space. Do you think the Maxline III “enterpise level” drives would be faster than the ones I have?
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My opinion is that you will not gain significant speed with the new drives. They are all 7200 rpm and the bigger buffer comes into play when you are playing back large files, or when you are doing multiple things and there is a lot of traffic on the bus..the larger cache will be able to keep up a little better with the handshaking.
But major speed gains…no. Now if you were to stripe FOUR drives together, rather tan the two, you would see significant gains, which is why 4-8 drive SATA RAID setups are becoming pretty common with lots of product out there.
Rich Rubasch
Tilt Media -
Guy,
Two drives striped counts as a real raid for SD DV. With two identical drives you certainly should be getting about 60 – 70 Mbps. That should do you fine for a while.
DRW
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For SD DV I would rather use the two drives seperately:
1. Your datarate needed for SD DV is so low that each drive can handle it easily.
2. You don’t lose any space with different drive sizes.
3. NB NB You double your risk with drive failure, because the raid 0 will lose all data on the Raid of one drive fails (AND THEY DO – ALL DRIVES FAIL EVENTUALLY). With two seperate drives, you lose only the data on the failed drive – the other drive’s data is still fine.Regards
Francois
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