On Sunday 14 September 2003 08:00 am, diego wrote: > El dom, 14-09-2003 a las 11:25, Anne Wilson escribi�: > > On Sunday 14 Sep 2003 12:32 am, diego wrote: > > > El s�b, 13-09-2003 a las 22:45, Anne Wilson escribi�: > > > > I thought of scsi2, but it's very expensive, so it would have to > > > > be worth a lot more. I planned a 7200 120GB disk. It would have > > > > very little on apart from the needs of the job. > > > > > > Have you thought about raid? Maybe you can try with that ide drive, > > > and if too slow get a second one to form a raid 0 (cache speed > > > would be the same, mantained speed about double). > > > > I've never worked with raid. From what I've read I came to the > > conclusion that lower levels of raid were not worth bothering with, > > and higher levels too expensive/complicated. I'm willing to hear > > that I'm wrong, though. > > That's not true, I'll show the most interesting cases in brief. Let say > you have a HD and it's running out of space, so you buy another one. > Then you'll have some programs/data in one and some in the other, but in > general you are only accessing one at a time (what a waste!! ;-) > > So what Raid 0 (raid for speed) would do is (for example) define a > virtual HD that has a sector of 32K when actually each drive has exactly > the half, so it reads/writes data joining sectors from both drives. That > way you have the same capacity as in the paragraph before but now with > the time a drive needs to give you a block you get 2. Useful, isn't it? > > The drawback is if one of both fails, you won't loose half the data but > ALL!! > > Raid 1 is for reliability as it writes exactly the same data in both > drives, so even having 2 drives you have only 1 drive capacity, but if > one fails, you still have ALL the data. > > Raid 5 is a situation where you have N+1 drives (minimum 3) where you > have N for speed (about N times faster than a single drive) and the > other one for reliability. Actually all of them work together for speed > and reliability, so a drive (ANY drive) may fail and you'll still have > ALL data. > > ALL of them are trivial to set up (if it seemed trivial to me... well > you know ;-) Anyway, I'd go for Raid 0 in your case as: > 1) it's cheap > 2) you'll get a 'virtual HD' about 2 times faster > 3) doing backups are easy and cheap, so if one of the drives dies you > won't loose all your data... > One thing everyone need to remember is that the IDE raid solutions that are available right now aren't really raid as most have come to expect raid. They use cpu processor power. This puts an extra load on the processor. The scsi raid systems have their own on board raid processing power. I currently use a mirrored system and was disappointed with performance. I'm happy to stay with it though, so if I lose a drive I haven't lost data. So if you are thinking pure peformance, you should probably not use the cheap typical ide raid. There are some more expensive ide raid controllers that do ues real hardware raid though. I just don't recall any off hand.
> > > If thinking on a fast AMD XP, just have a very close look at the > > > heatsink+fan as it easily maybe insufficient or be too noisy... > > > > That could be very important. I'll make sure I get recommendations > > from my supplier for efficiency and noise. > > > > Before I actually order anything I shall make a composite document > > with all the recommendations I have had from everyone, so that I take > > maximum advantage of everyone's experiences. > > Depending on how close you will be to that computer, noise will be a > factor. If you're going to be close to it many hours, take one with less > than 30dB of noise. > > As your future CPU seems it's going to be near 100% many hours, cooling > power is esential. > > I recently bought a "Aerocool Deep Impact DP-101" and I'm quite happy > with it, but get more info from the real experts... > > > Good Luck with the project.
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