RAID5 speed question.

Keith kwoody at
Mon Oct 31 22:01:29 UTC 2011

Have an ancient 4.1R mail server to replace.
It has about 3000 accounts. Usual /var/mail to store mail.

/var/mail is RAID5 on an old Dell PERC3 card. Its worked
pretty well and have lived through 3 drive failures over
the years.

New Dell box with a PERC5/i. Same drive setup, a 500GB
RAID5 for /var/mail.

I do an ls -l in /var/mail on the old 4.10 machine and I get a directory
listing in about 2 seconds. This is about 3000 mailboxes.

On the new machine running 7.3 with the PERC5/i I rsync'd /var/mail and do
an ls -l and it takes a full 22 seconds to get a directory listing.

A plain ls in /var/mail on both machines is instantaneous.

I know RAID5 is not 'optimal' for this but I'm surprised at the difference
in how long it takes to do a directory listing using ls -l on the new
machine compared to the old one.

The new array is 500GB compared to about 36GB on the older machine.

Shouldn't a long directory listing be faster on the PERC5/i compared to
the old PERC3?

Other than that the new machine in all other aspects is faster, a lot


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