Just a quick raid question?

[2canSAM]

I currently have 4 10.2 gigs in raid 0 which has really smoked. If I replace those with 2 20 gigs will the preformance be about the same. Does having the stripe broken across 4 drives improve speed over having it striped over on 2?

[linux_guru]

You wont notice much difference striping across 4, as opposed to striping across 2. I cant understand why anyone bothers with Raid 0, for the minimal performance gain you get.

If you lose one disk, you lose everything. You'd be better off doing Raid 5, across 4 disks. That way, one disk can go bad and you dont lose your data.

[darkmallard]

RAID 0 is faster than RAID 5 because it doesn't have to write parity information. Like linux_guru said, you have no redundancy with RAID 0. If you want fault tolerance, get a third 20GB drive and go with RAID 5. It's faster than RAID 1 (Disk Mirroring). You must have at least 3 physical drives for RAID level 5. The performance would improve if the hard drives were faster, if the controller supports the faster transfer rates, and if the controller can write to more than one drive at the same time. There is only a performance gain comparing 2 drives to 4 drives if the controller can write to each one at the same time.

[dosmastr]

i beg to differ about RAID 0 not increasing performance.
i have read about many high end gaming systems with a dual IBM 75GXP RAID 0 setup
with 2 75GB drives on system pulled in excess of 66mbps SUSTAINED (the benchmark only went up to 66mbps) for the first 30GB's of the disk, and averaged i think 37Mbps.

in any case, i am about to start my own raid up with a similar setup except using 2 30Gb versions. I'll let you know how/if my performance changes, Linux_guru. i'll post a thread in this area.

as for 4 drives over 2 i would think that 4 drives would be better because the load is better distributed.... however, i have no hard fact behind this just so idealistic thinking.

sorry darkmallard i have to disagree, wouldn't the parity data be written at the same time as the other 2 drives write? ( in a RAID 5) if so, the i disagree, if not, then i apoligise, and would have to agree with you.

as for losing one disk
how often does that happen with modern hard drives in home user systems?

[This message has been edited by dosmastr (edited 02-08-2001).]

[dosmastr]

hey 2can
what kind of throughoutput do you see on the rig you have anyway?

get HD tach and measure it.

if i recall you said you have maxtor drives, i have read that those aren't too good for speed ( i have one it only does 20mbps, as opposed to both of my ibm drives, which without being in the RAID, pull an average of 35mbps )

[dosmastr]

well Linux_guru

i don't know what kind of RAID 0 you were running, but this one is now pulling 60MBps average, 75MBps maximum and 38MBps minimum.
perhaps you had a decade card with a couple of seagate drives.

2canSam how fast does your run????