SATAII/Raptor/RAID0/RAID1

Markjsca · 10 Oct 2006 at 15:45

What the fastest? SATAII disks run at 7200rpm and claim to be 3Gb/s. Raptor disks are 10000rpm but the throughput is....???

What I'm wondering is which is faster for drive access/throughput?

Would RAID0/RAID1 speed either up?

I'm making my shopping list for a new PC running XP Pro but would obviously like to make it Vista compatable. What i'm trying to figure out is what drives/combo of drives would be best for Windows/Program Files/Games?

Thanks for your help.

Mark

rpstewart · 10 Oct 2006 at 16:14

The SATA II standard theoretically allows signalling at 3Gbs with an 80% efficiency (due to overheads in the data encoding method) yeilding 300MB/s of data transfer. HDDs cannot get anywhere close to this figure in sustained transfers with the best 7200rpm drives topping out at about 75-80MB/s. Raptors will give a better sustained transfer, maybe up to 90MB/s but their real benefit is in random seek time - 5ms or so vs 8ms or so for 7200rpm disks. This doesn't seem like a lot but when you're accessing a lot of files across the whole disk like you do when booting Windows then it makes a big difference.

RAID0 will give you better transfer rates from either type of disk although there won't be much (if any) improvement in random seek time. RAID1 is mirroring for reliability and won't give any improvement in either seek time or transfer rate and is actually quite poor when writing.

Markjsca · 10 Oct 2006 at 17:13

Thanks for the detailed answer rpstewart

That's exactly the info I was looking for. I was thinking that the 3Gb/s figure seemed a bit irrelevant due to how much data the drive can supply per second...

I'll probably go for a raptor raid 0 then for windows/programs/games...

Does RAID 0 split the file accross both (or multiple if >2) drives? i.e. theoretically the file is written and read twice as fast due to each drive only having to do half the work?

If this is the case...two 36gb drives in RAID 0 would be significantly better than one 74gb drive, is this correct?

rpstewart · 10 Oct 2006 at 18:29

Markjsca said:
Does RAID 0 split the file accross both (or multiple if >2) drives? i.e. theoretically the file is written and read twice as fast due to each drive only having to do half the work?

Yeah, data is split across however many disks are in the array. Reads are quick - maybe 1.5x a single disk with 2 disk array, writes I think may be slightly quicker but I can't remember. Read performance is what most folk look for anyway.

Markjsca said:
If this is the case...two 36gb drives in RAID 0 would be significantly better than one 74gb drive, is this correct?

Yes and no. The read performance will be better with RAID, random seek time will be pretty much the same on both, as will writes I think (see above). Reliability however is a different question - with RAID0 if one disk dies all the data is gone. It's the same with a single disk of course but you've got 2 chances in RAID0.