Removable disk problems

From: <Jim.Lovell_at_email.protected>
Date: Tue, 22 Aug 2006 16:11:12 +1000

Hi everyone,

This email didn't get through before I think. Trying again...
>-----Original Message-----
>From: Lovell, Jim (ATNF, ANUTECH - Acton)
>Sent: Tue 8/22/2006 2:40 PM
>To: vlbiobs_at_atnf.<!--nospam-->csiro.au
>Cc:
>Subject: Removable disk problems
>
>Hi everyone,
>
>In getting ready for the experiment tomorrow I've discovered some
>problems with the removable disks that are quite serious. As Tid is
>the only station using removables this time this doesn't affect
>anyone else for tomorrow but I'd suggest that everyone runs some
>tests on their removable drives soon.
>
>In the process of installing and testing the disks I ran Chris'
>diskspeed program on individual disks and found some had good data
>rates (~355 Mbps) while others were much worse (~160 Mbps in some
>cases). In a four disk RAID configuration I was getting rates
>anywhere between 200 and 900 Mbps and could see that some disks
>were taking longer to write than others by looking at the red
>lights on the front of the caddies. I also noticed that if I gave
>the disks a little push I could increase the data rates! This
>seemed like a connectivity problem to me. Anyway, last night, with
>the disks in their caddies and good looking rates, I ran diskspeed
>until the disks filled up. The resulting data rate (Mbps) vs time
>(s) is in test.gif. Note the horrrible performance! The
>configuration couldn't sustain 256 Mbps at some times!
>
>So this morning I took apart the caddy system and connected the
>hard drives directly to the IDE cables, thereby removing the
>possible flakey connections. The result (for 7000 sec) is in
>nocaddy.gif and the difference is remarkable! (although I don't
>know what caused that slowdown around 1600-2600 sec).
>
>So I'd strongly encourage everyone who uses the removable disks to
>run some data rate tests to see if they also have this problem!
>
>For tomorrow's experiment I'll be using the disks in this hard-
>wired mode. The disk change will take longer but the data should be
>good.
>
>Cheers,
>Jim
>with the
>

<div>
<img src="../../att-0600/test.gif" alt="test.gif" />


Received on 2006-08-22 16:11:49