Re: RAID 5 performance problems

Peter L. Ashford (ashford@sdsc.edu)
Thu, 3 Apr 2003 14:13:14 -0800 (PST)


Jonathan,

> > The ONLY reason that I can think of to use round cables would be for
> > looks. From a performance or reliability standpoint, they are a waste of
> > money. I routinely build systems with dual 8-channel IDE RAID cards
> > (3Ware 7500-8) and 16 disks, and ONLY use flat cables.
>
> I use rounded cables in my case for a few reasons:
> - The distance between my promise and my drives is small yet the promise
> cables are long, the rounded cables I have are 12" long and fit very neatly
> - The promise cables had two IDE connectors but I only wanted to put one
> drive per channel; the rounded cables are single cables
> - Air flow; because of my small casing the flat promise cables were
> contricting the airflow quite a bit, the rounded less
> - flexibility; I found the flat cables hard to bend in to place whereas the
> round cables you could twist easily
>
> I've added a link which should make it clear that rounded cables in my case
> are a benefit to me. What I was worried about was that they could be
> inferior quality and thus be a factor in my raid performance.
>
> http://www.datzegik.com/DSC00056.JPG

Check out 'http://www.accs.com/p_and_p/TeraByte/cables.html', to see why
round cables are not needed. Careful cable routing can easilly overcome
the issues you have. When you have a large number of cables, the flat
cables can stack, but the round cables just make a big bundle.

Also, 3Ware sells 80-conductor/40-pin cables with two connectors in 18",
24" and 36" lengths.

I've built systems in cases that are similar to yours (Antec or Chen-Ming)
with similar numbers of drives, and had no problems with flat cables to
five disks, a CDROM drive and a floppy drive.

Good luck.
Peter Ashford

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