[ale] disk i/o at 1,000 MB / sec, woohoo!

[Lightner, Jeff]

FYI:  On the Dell integrated RAID controllers (PERC and SAS) they
usually have an initialization option that lets you low level format the
drives from the controllers instead of having to dd to the whole RAID
set.   Slower to do each I'm sure but it gives me more of a comfort
factor to blow away the RAID set and initialize the individual drives.

Interestingly I found with the RHEL5 boot CD if you go into Rescue Mode
then "Skip" the attempted mount of Linux partition (as /mnt/sysimage)
you'll drop to the command line and can mount manually, redo partitions
and/or dd to your heart's content.   We just retired our last RH 7.3 and
RH 9 servers last week that had no RAID controllers.   I also blew away
some other systems the Dell PERC controllers.

-----Original Message-----
From: ale-bounces at ale.org [mailto:ale-bounces at ale.org] On Behalf Of Greg
Freemyer
Sent: Wednesday, August 25, 2010 11:32 AM
To: Atlanta Linux Enthusiasts - Yes! We run Linux!
Subject: [ale] disk i/o at 1,000 MB / sec, woohoo!

I needed to wipe a 1.5 TB Raid 5 array on a demo unit today before
returning it.

My expectation was a few hours or more to do it.

I booted up a linux boot cd and started dd  (actually a customized
version known as dcfldd.  It's my own custom boot CD.).

Its running about 1 GB/sec or 1,000 MB/sec.

My wipe of 1.5 TB should finish in less than 30 minutes.

Even if you consider there are 6 drives in the array and divide the
throughput by 5, that's still 200MB / sec / drive.

That is the fastest I've seen yet!  Requires both extremely fast
drives and an extremely fast raid controller.

I normally work / test SATA drives.  A really fast sata is about half
that speed.  I haven't tested hardware raid performance recently, so I
don't know how unusual a 1,000 MB/sec aggregate throughput is.

fyi: 15K rpm SAS drives in a modern Dell 2U unit (PowerEdge R710).

Greg
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