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LTO-3 Autoloader Performance Issues

Justin Raynes
Occasional Visitor

LTO-3 Autoloader Performance Issues

Hi,

We have an old Overland Storage tape library with a HP LTO-3 tape drive which hasn't been used in some time. I have the library connected to a ProLiant DL320 G5p running Server 2008 R2 via an Adaptec PCI-e SCSI card. Last night I tried to run a backup job in Backup Exec 2010 and noticed an unusually slow transfer rate of 120mb/min. When logging into the web interface for the autoloader I could see the status of the drive switching between "Writing" and "Loaded" every 5-10 minutes. Thinking this has something to do with the drive itself I downloaded Library & Tape Tools and ran an assessment test which completed successfully but in the logs there was a warning that the "device is polling on id 7" and this could impact performance. How should I resolve this?

Thanks,
Justin
3 REPLIES
LTT Team
Valued Contributor

Re: LTO-3 Autoloader Performance Issues

120mb/min is way too slow for the LTO-3 drive. But the performance depends on many factors, like the system performance, the cabling, HBA etc..

Can you generate a support ticket from L&TT and send it to ltt.team@hp.com ?



Marino Meloni_1
Honored Contributor

Re: LTO-3 Autoloader Performance Issues

The slow perf may be caused by a lot of factors
usually the source of the data is the main cause, and if the data are not flowing fast enough to keep the buffer full, the drive will slow down and stop untill the new data arrive, then restart and again wait for data.

There is a test in LTT (dev perf test) that allow a write data from the host memory to the drive, so no source involved and you can then check only the part from the host, to the LTO

another reason could be that the head need cleaning, as the LTO has not been used for logn time, some contamination may occurs on the head depending of the environment

the support ticket will probably clarify the cause.

tanus02
Occasional Visitor

Re: LTO-3 Autoloader Performance Issues

It sounds to me like your server HBAs are polling too often.

At a quiet period on your storage network check the led activity on your library.

I have administered aprx 90 DL380s with dual HBAs. The polling should be a blink every 3-5secs for this amount, it shouldnt look like data activity on a switch. (flickering)

I have encountered the problem a number of times but not recently, so please excuse my lack of knowledge in pointing you to the correct tool.

I believe there is a util to upgrade HBA firmware by HP. If I remember correctly there is an option in here that can modify the polling interval or disable it.