LTO-3 tape performance tuning

[resonate Profile]

I have a HP Ultrium 3 LTO-3 tape drive which is running the latest firmware. I'm only getting about 50MB/s on large files and 36MB/s with image files using 64K block size. The drive should be able to do 80MB/s uncompress and I'm not getting any where near that.

The source drive is SATA 3 and I can get 150MB/s+ copying 4GB files to other drive, so source read performance is not a problem here.

Anything I can do to improve the performance?

Hardware Specs
********************************
Windows 7 x64 SP1 Ultimate
Intel Core i5-4670
16GB DDR3
Adaptec 29320ALP SCSI HBA
HP Storageworks Ultrium 960 (firmware G66D)

[Administrator]

Hello,

how old is the drive? How old is the cassette?

Best regards

The staff

[resonate Profile]

LTO-3 media is brand new. Drive is atleast 5 years old but was hardly used.

Is there any kind of debug mode to see prove delays are coming from?

[Administrator]

Hello,

thanks for the fast asnwer. Tape cassettes and tape drives wear out with time and this can affect write performance too.

We suggest to download the HP Library and Tape Tools ( http://www8.hp.com/us/en/products/stora ... b=features ) and check the health of your tape cartridge.

Best regards

The staff

[resonate Profile]

The media is brand new so its not that. I have tried two different tapes. I downloaded the tape tools and the drive diagnostics pass. and head

Head life : Great margin, 96% life remaining
Reposition life : Great margin, 99% life remaining
Load/unload life : Great margin, 99% life remaining

[Administrator]

Hello,

ok, the results of the test are really good.

Sadly the only advice we have is to enable the compression. Or try other block sizes - but 64K should be fine in your case. Generally speaking, greater block sizes produce greater performance but they are not always supported by the tape unit.

Best regards

[resonate Profile]

HP Tape diagnostic performance results are as below using 1MB I/O with 64KB block size

|__ Device Performance Test Started on Drive (Ultrium 3-SCSI) (Tape0)
|__ Testing with 2:1 Compression Ratio
|__ Opening Tape Drive Tape0
|__ Rewinding Tape
|__ Spinning Up
|__ 4.0 GB written in 45.8 seconds at 87.4 MB/s (Min 86.5 MB/s, Max 88.1 MB/s)
|__ Rewinding Tape
|__ Spinning Up
|__ 4.0 GB read in 45.6 seconds at 87.8 MB/s (Min 87.0 MB/s, Max 88.6 MB/s)
|__ Rewinding Tape
|__ Closing Tape Drive Tape0


I've tried different combinations of hardware compression on and off, on I get about 50MB/s and off I get 56MB/s. So there is no other recommendations?

[Administrator]

Hello,

you could compress the backup in a single "big" zip on a local or external disk. And then write the file to the tape.

It's a good test to check if there are margins of improvement.

Best regards

The staff

[resonate Profile]

Why would I use software compression when hardware compression is better than any compression software can do?

The files I'm backing up are video files and are already highly compressed. Thanks for the help anyways.

Something the product could probably improve on is some type of debugging to check the performance. NetBackup has SIZE_DATA_BUFFERS and NUMBER_DATA_BUFFERS values that can be turned and verbose logging shows where delays are coming from.

[Administrator]

Hello,

we suggested the "single zip test" not for the compression. Storage systems give their best performance with big files, because it's a sequential read operation. It could be useful to identify bottlenecks.

Thanks for your suggestion, we took note.

Best regards

The staff

[pmk Profile]

Hello, resonate

For best performance try block size 256kB. Try also ssd drive as a source drive.

best regards,
pmk

[pherschel Profile]

Sounds to me like a controller / drive problem / limitation. I switched to SAS controllers. IBM-HH SAS LTO-3 and Quantum LTO-4 SAS drives and I get 2 Gig a minute with a 64 K block size and drive compression on. Thing is once the drive starts giving me write errors its time to replace it. Some drives last 2 years others much less. Quantum has a nice drive properties / cleaning warning display in device manager properties.

Good luck