On Wed, Dec 15, 1999 at 11:27:36AM -0400, The Hermit Hacker wrote:
> On Wed, 15 Dec 1999, Jeff Hoffmann wrote:
>
> > > my preference tends to be software raid...whatever I've ever seen as far
> > > as hardware raid is concerned has been quite slower then software
> > > raid...and this is with high-end servers...
> >
> > i kind of question this, and here's why: i just set up a linux dual
> > P3/256MB with 4 software raid 5 volumes and even loading data into one
> > of the databases slows it to a crawl. i've been looking around because
>
<snip>
>
> Most of my RAID tests are on Solaris+Disksuite...with good drives
> in the machine, my writes are something like 18MB/s to the drive, stripe'd
> and mirrored...I think reads worked out to be 19MB/s...(bad drives, same
Ah, this would be a RAID 0+1 setup, then? Very different from Jeff's RAID
5 configuration. I'd be willing to believe that software RAID 0+1 _could_
be faster than most hardware (it's just shuffling and dupping blocks
around to different drives, which could be done with clever pointer
twiddling) but calculating parity bits in hardware for RAID 5 had got
to be a win, doesn't it?
As it turns out, I'm speccing a similar machine right now, myself,
and I've been running into statements like yours re: software RAID that
surprised me.
> setup, same machine, same OS, were net'ng me something like 3MB/s...really
> killed performance *grin*)
Hmm, bad drives as in broken, or slow?
Ross
--
Ross J. Reedstrom, Ph.D., <reedstrm@rice.edu>
NSBRI Research Scientist/Programmer
Computer and Information Technology Institute
Rice University, 6100 S. Main St., Houston, TX 77005