Not getting very good performance on the 3590
Customer has just installed his 3590-B11 Tape drive and through testing
has determined that he is getting only 2mb/sec throughput.
I first had the customer upgrade the device driver to Atape.driver 18.104.22.168.
To determine the throughput of the tape drive only, leaving the hard
disk out of the picture run this command:
This command builds the data in memory first then writes it to tape thus
taking the hard disk out of the picture.
time tapeutil -f /dev/rmt0.1 wtest -b 262144 -c 1 -r 500
131072000 bytes written
Real Time = 13.84 seconds
The tape drive is running at expected rates.
Next I had the customer use his normal backup command, tar in this case
and backup to /dev/null. This provided a throughput of 4mb/sec.
Customer should expect to push the 4mb/sec number but will not achieve 9mb/sec
due to the bottleneck of the disk drives.
Customer was receiving only 1-2m earlier. I explained that the new
driver help that. I also had customer set block size of the tape
drive to 256k (262144) which is the optimal block size for the 3590.
NOTE: Make sure the buffer size of the backup command
being run is a multiple of the block size.
Example: If the block size of the tape drive is 262144,
then the command being run needs to be
tar -b512 -cvf /dev/rmt0 /filesystem
tar -b512 -xvf /dev/rmt0
Support Line: Not getting very good performance on the 3590 ITEM: BN4947L
Dated: September 1996 Category: N/A
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