I believe this has been mentioned here before, and I've experienced this
myself. The LTO drives on our backup system are SCSI connected. On at
least two occasions, the scsi bus has experienced some kind of
disruption to cause it to slow down to SE speeds. When I could normally
get 20+ MB/sec, the affected drive would not write at speeds above 5
MB/sec. Rebooting the server fixed the problem. If this happens
frequently, then it's likely a hardware fault. I was able to confirm
the slowdown by checking the system logs or dmesg. It would clearly
show the scsi bus error, the devices affected, and would give the exact
speed or mode that the card was now operating.
-Jon
> One of our seven LTO drives will not read or write above 1.6 MB/sec.
> In fact, it stays at exactly 1.6 MB/sec while in use. Our other
> drives average 10MB/sec, and spike up to 20+ MB/sec. I replaced the
> drive, with no effect. We are using NetBackup datacenter 4.5 on a Sun
> V880 running Solaris 8. If it's not the drive, where should I
> start checking for the error - media server, robot, or cables between?
>
> Thanks
>
> Alec Browne
> Systems Administrator
> The Institute For Genomic Research
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