External USB Hard Drive
Had an interesting problem recently concerning an external USB hard drive.
A client of mine is using external drives for backup. The drives they were using were 120gb capacity, and were becoming too small for the amount of data that we needed to backup.
I recommended that we increase the size of the drive in the external cases to 250gb which would then give enough space to keep the most recent 3 backups on the drives. (They use 2 drives and rotate them.)
I purchased the new drives and took the old drives out of the cases and installed the new drives. Connected the units to the server in order to partition and format them. When I went into disk management to carry out the formatting process the drive would only show up as 128gb capacity (the alarm bellls should have started ringing then).
I took the drives back out of the cases and connected them directly to an IDE connection and they then showed up as the correct capacity (250gb), so I partitioned and formatted them and then put them back in their cases. Connected back up to USB and checked capacity in explorer, showed up as 250gb.
Each backup is approx 45gb and I checked each morning to ensure the backup was working correctly. This was ok for the first 2 days and then on the third day I could not log in remotely to the server to check the backup and had also not received an email at 6.ooam to tell me that the backup was successful. Then I had a call from the client to say that the server appeared to have frozen.
Went onsite and there was an error message on the server screen to the effect that the write delay had failed while writing to the external drive. As I had turned off write delay on the external drives I wondered what was the problem. Checked the file sizes on the drive and noticed that the total of the file sizes was just under 128gb. I rebooted the server and ran a number of checks on the drives which did not show up any problems.
Long story short, it turned out that the problem was caused by the external cases and the fact that were only seeing the drives as 128gb. After a bit more head scratching and without doing any further investigating via google and other blogs I decided to purchase 2 new and differnt brand external USB cases. Voila, after installing the drives in the new cases and connecting them to the server I was able to copy over another 20gb without any further problems.
Admittedly the original cases were about 3 years old so the firmware in the cases was not able to handle todays much larger drives.
posted by Peter K @ 11:47 AM
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