HP Tape Tool Test

[NCBPAC]

I have an HP 1/8 G2 1760 Autoloader and have been having some issues lately. I have ran the LT&T test and get very low write rates from 2MBs to 12MBs. I thought this would have been a lot higher since I have am using and U320 controller. Are those rates normal for the test.

[thomasr]

• I have an HP 1/8 G2 1760 Autoloader and have been having some issues lately. I have ran the LT&T test and get very low write rates from 2MBs to 12MBs. I thought this would have been a lot higher since I have am using and U320 controller. Are those rates normal for the test.

Well, it depends on which test you're running.

If you're running the drive test, where L&TT creates a data set in RAM and sends it to the tape drive, then this is pretty slow.  Your expected performance on the tape drive should be in the 80MB/second range on a healthy tape drive with good media, depending on how fast your server is and some other factors.

If you ran the drive test, where L&TT reads from the hard drive to simulate disk read speed during a backup, but doesn't write the data anywhere, then your numbers indicate a slow system, but aren't exactly surprising.   Depending on the disk controller (SmartArray vs. JBOD), the striping, the fragmentation, the contention from other processes, the ratio of small (say, 20K and less) and tiny (1K and less) files, how deeply nested your directory structure is, and how long your file names are (and a few other things) -- 5MB/second is not unusual, even if it's not good.

So -- give us some more details about exactly which test you ran, and what your server configuration is (model, processor, RAM, disk controller, disk configuration, etc.) and we might be able to help a bit more.

What performance is your backup application reporting when you run a real backup?

Have you run Library and Tape Tools and done the media and drive tests?   These would help determine if the drive itself is having problems.

[NCBPAC]

I am running the test on an HP Proliant DL380 G5 DUAL X2.4GHZ with 8GB RAM.  The current test I am running is a Read/Write test to tape from the TEST menu.  4G, 64k Block,2:1 compression. Standard test.

To write 4G it indicates 35minutes to complete the test on a brand new tape.

[thomasr]

Sounds like it's time to generate a support ticket from Library and Tape Tools. 

I can think of two reasonably likely causes of this poor performance.

1) Tape head is worn and the drive needs to be replaced.   L&TT will show this.  The application may show it, too, if you right-click a piece of written media and see if it flags lots of write errors.

2) Possibly you've got a poor SCSI cable, total cable length is too long, or the terminator is failing.   Try swapping out the cable, use the shortest possible cable (Looks like maximum bus length -- all cables combined -- for U320 is 12 meters, but make sure you're well under that), replace the terminator on the library or any other terminators.