Rambling on with RAID questions

[kirkdickinson]

I am thinking about building a new computer and the MB that I am thinging about using has an option for EIDE RAID. I understand a little about RAID from my reading on the net, but have some questions that I would like some answers to.

1. With RAID 0 can I expect twice as fast access time with two drives and three times as fast with three drives? Or is that only in theory?

2. If I did a RAID 0 with two IDE drives (9ms 7200RPM) would it really be any faster than a single SCSI Ultra 160?

3. What are the advantages and disadvantages of 0+1 vs. 1+0?

4. Any opinions of the built in RAID on the Iwill DVD-266-R Motherboard?

Thanks,

Kirk

<P ID="edit"><FONT SIZE=-1><EM>Edited by kirkdickinson on 05/27/01 09:40 PM.</EM></FONT></P>

 

[mjdunn]

With Raid 0 you can expect to be almost twice as fast with two drives...the increase isn't that impressive after 3.

Raid 0 IDE faster than a single SCSI U160...don't know

Raid 0+1 is striped and mirrored - never heard of 1+0 but I am sure it would be the same thing. Raid 0 or Raid 5 don't bother with the others if you are looking for performance.

Don't know about the Iwill built in raid controller...who is it made by? Is it made by promise? If so that controller is pretty good.


96.3 % of Statistics are made up.

 

[kirkdickinson]

I believe from what I read, that there is a difference between 0+1 and 1+0. One would be Mirrors of Stripes and the other would be Stripes of Mirrors.

When combining two different types of RAID you have an hierarchy. In my mind is it confusing thinking about it with only four drives, but with six, it makes more sense. You can combine six drives two different ways.

1st - as three striped drives at the first level, with each sub level containing two mirrors.

2nd - as two mirrored drives at the first level, with each sub level containing three striped drives.

Here is one place that I have been reading about RAID:
http://www.pcguide.com/ref/hdd/perf/raid/levels/multXY-c.html

I don't know which RAID chip the IWill MB uses, but on their website, it says "Dual AMI ATA/100 IDE RAID Controller" Here is the page:
http://www.iwillusa.com/products/spec.asp?ModelName=DVD266-R&SupportID=

THanks,

Kirk

 

[Guest]

I too was thinking of IDE RAID. You have to bear in mind that you will not benefit from huge performance gains in everyday tasks. Where as with SCSI you will see bigger gains, BUT(!) SCSI is aimed more at the professional so it has a price tag to match. You will really reap the benefits of IDE RAID if you do a lot of disk intensive tasks, such as video editing. If you do want to have IDE RAID, then I would go for 2 drives in a RAID 0 configuration (Striping - using the largest cluster size for extra performance). You do not lose any storage space this way (assuming that you use two drive with the same capacity). Therefore decide how much storage space you need and buy two identical drives, each being half that capacity. For example, if you need say 30GB then buy two identical 15GB drives. If your system data is CRITICAL then go for a mirrored configuration for the insurance, with striping to aid performance. This means thopugh that you need to buy more drives AND lose half the overall capacity of the drives.
What I was thinking for my system, was a U160 SCSI 'system' drive (where the OS and apps will be installed) and a 120GB (2 x 60GB) IDE RAID 0 configuration for video and graphics work. The best of both worlds .
If i were you just go for a RAID 0 configuration using the largest cluster size (if you arent concerned about slack space) using two identical FAST EIDE drives. This will have a good cost/performance ratio AND you dont lose any storage space!

 

[Guest]

1. With RAID 0 can I expect twice as fast access time with two drives and three times as fast with three drives? Or is that only in theory?

Most benchmarks will show a similar result, but only an objective IOMeter figure can answer that.

2. If I did a RAID 0 with two IDE drives (9ms 7200RPM) would it really be any faster than a single SCSI Ultra 160?

My Quantum Atlas (10K rpms - U160SCSI) can barely keep up with my 4-disk Striping array (32K clusters) in everyday use. your seek times will not improve, because you'll still have one disk at the time seeking your data.

3. What are the advantages and disadvantages of 0+1 vs. 1+0?

Go for RAID0 .. why sacrifice the extra disk & speed for an array you'll probably never get to rebuild ?