Questions about Raid

[hity645]

Im thinking of buying 2 36GB raptors and doing them in a raid. A raid is where data is written evenly across two disks right? Currently right now i have 2 250GB drives, now i can setup one raid for the raptors and then setup another for my 250s? And this would show up in windows as 2 drives, one close to 70gb the other close to 500 right?

[xonik]

RAID is a very broad term but usually it defines one or both of the following functions:

Striping - distributing different chunks of data evenly across all the drives in the array
Mirroring - distributing the same chunk of data to every drive in the array

What you wanted is striping. RAID 0 describes the most basic implementation of striping. Note that RAID 0 offers no redundancy or protection of your data. As different chunks of data are being transferred to each drive in the array, the array can't function if one of the drives fail or goes offline. In other words, if any drive in the array fails or goes offline, ALL of the data in the array is lost. That's the danger behind RAID 0.

The upside is that the array performs faster than any one drive in the array, under many conditions. Also, the individual drives in the array show up as one drive, which can be convenient.

Okay, now that the theory has been outlined, let's move on to your selections.

1. The 36 GB Raptors aren't anything special. They are slow for a 10,000 RPM drive, hardly performing better than high performance 7200 RPM drives. They also run hot and loud. In RAID 0, two 36 GB Raptors perform basically on par with the quieter, cooler, better performing 74 GB Raptor. Definitely buy one of these instead of 2 36 giggers.
2. Don't run RAID 0 for general storage of data. You risk losing it all if one drive fails, as I explained earlier. That's 500 GB down the drain, in the case of your 2 x 250 GB proposal. Besides, general storage is not sensitive to hard disk performance. You wouldn't notice a performance difference anyway.

[hity645]

Thanks!

[Brav]

I have 2 36g raptors - will i benefit from ditching them and going with 1 or 2 74s, or a really good pair of 7600rpm drives? Price is not really an issue, just not willing to pay if it doesnt make a difference. Also Running RAID 0+1 (4 drives) - does this realy speed read times up?

[xonik]

I have 2 36g raptors - will i benefit from ditching them and going with 1 or 2 74s, or a really good pair of 7600rpm drives?I think you would benefit from a single 74 GB Raptor. It performs just as well or better than the 2 x 36 setup, but it'll also run quieter, cooler, and more reliably. Also, 2 x 36 GB drives doubles the theoretical chance of losing all your data to a drive failure. In practice, it may increase the chances even more, because the 36 GB drives are from the first generation of production.

7200 RPM drives are plenty fast for many things. If you were on a budget, I would have recommended a recent Hitachi or Maxtor unit. Since price isn't an issue, I think you'll find that the single 74 GB Raptor is the best investment of your moneAlso Running RAID 0+1 (4 drives) - does this realy speed read times up?RAID 0+1 has the speed of RAID 0, within +/- 5%, but the redundancy of RAID 1. In a sense, it's the best of both worlds, but of course you need four drives to accomplish this. Also, the total usable capacity will be half of the total drive capacity, due to the redundancy of this RAID level.

[Brav]

Thanks - so RAID 0+1 is strictly for redundancy, and does not increase read times correct?(since it can read the same info in 2 places at once, theoreticaly)

[xonik]

Like I said, it has the speed of RAID 0. In other words, the read/write performance is comparable to a regular RAID 0 setup. Like RAID 0, however, access performance is no better than a single drive, sometimes worse.

Think of RAID 0+1 as a mirrored RAID 0 array, or a striped RAID 1 array. This is basically how the technology works.

[Brav]

Alright, thanks - just making sure, becuase someone was telling me otherwise :rolleyes:
:confused:

[xonik]

Yeah, for a second opinion you could read this article,

http://www.storagereview.com/guide2000/ref/hdd/perf/raid/levels/multLevel01.html

[g33zy]

such a good thing I looked through before starting a thread, I was going to ask the EXACT same question. Was thinking about doing the SAME thing....thanks guys