StorageWorks 1/8 G2 Tape Auto Loader bad performance, LTO3 tapes faster than LTO4?

[Joe_Bez]

Our HP LTO3 autoloader died out of warranty a few weeks ago, so it was time for an upgrade. We dropped in a HP Storageworks 1/8 G2 LTO 4.

It’s connected via LVD320 , on the old LTO3 autoloader we saw a local backup rate of around 5 to 5.5 GB a minute, But with the new LTO4 unit we only saw 3.5 to 4gb a minute at first.. But its now got even worst dropping right down to 2gb a minute!.

The 3.3tb Array is RAID5 and is SAS attached and is reporting zero problems, we have done defrags with Prefectdisk 10 and its reporting to be close to 100% performance.


The Server is used only by graphic designers, so the file types are all graphics types. So I know not to expect good compression, the best we see is 1.4 to 1 but when using the LTO4 tapes this has now dropped to 1.05 to 1 or on a few occasions worst than 1to1!


What I have noted is if we use LTO3 tape in the LTO4 auto loader we get better speed and better compression??!


Whats going on here?

Windows Server 2003 sp2,
Backup Exec 11d rev 7170
Thanks

[Ganz]

Hello Joe,

Few things to ensure we are running in a compatibile environment ::

1. The LTO driver should be running at version 1.0.6.1.
2. The Drive and library firmware should be the latest.
3. HP recommends the use of HP tape media.
4. In Library and Tape tools there is an option to run a Data Compression test. Run this test with LTO4 and then an LTO3 tape and compare the results.
5. There is a "SysPerf" test available to find out the Disk I/O throughput .
6. Run the DevPerf test to check the performane of tape drive. This will rule out any hardware issue with the drive.
7. Extract a support ticket and attach the same for further analysis.

Ensure you are using a compatible HBA with the autoloader by referring to the EBS compatibility matrix ( http://h18006.www1.hp.com/products/storageworks/ebs/pdf/EBSMatrix-0210.pdf) and the quick specs of the server.

[Ralf Loehmann_2]

Hello Joe,

that might be also a simple performance issue, because 3.5 GB/min is 58MB/s and with 1.4to 1 compression it might be below the minimum performance. Here this might help to get the performance back into a good range, which will also help to keep tape drive and media healthy. Specially read the section: How important is performance - Wear and tear
Right above the link, I put you right into the document, because this trooubleshooting flow helps to address this issue:
http://h20000.www2.hp.com/bizsupport/TechSupport/Document.jsp?objectID=lpg50460#A2

Hope this help to understand the issue with minimum performance and what can be made better. If the data of that system still fits on LTO-3 media you might still use this tapes, because than the minimum native data rate (for uncompressable data) goes than from 40MB/sec to 25 MB/sec.

Hope that helps to understand the issue and get a solution for it.
Ralf.

[Joe_Bez]

Is is known what the minimum throughput is for a LTO4 to be 'happy' ?

an update, todaye we had a new Autoloader delivered and we installed it along with updating everything we could.
Drivers, fireware, scsi card firmware, backup exec, etc etc.

We are still not seeing the 5+ gb we have seen, but its much better now. I have done a few tests and we are seeing 4 to 4.5gb now. And this is with the backup running during the day with a busy server.

Not perfect but its enough to get the backups done in the window we have, as long as it does not slow up again.

Its also looks like the media might not be helping, we have some Sony tapes (the LTO3's are HP) and i did some tests with the HP tape tools and they dont like the media at all!

[Uwe Zessin · Accepted solution]

It depends on the drive, e.g.:
Ultrium 1840 - 40-120MB/s
Ultrium 1760c - 33-80MB/s

[Joe_Bez]

This is a 1760..
I cant belive the array is running lower than 33MB/s??

Using the Sys Perf within Tape tools im seeing around 80MB/s on all the logical drives?

[Uwe Zessin]

The speed I have given is the 'native' value. If the data is good compressible you need to deliver *more* to keep the drive streaming.
E.g. if it allows a 1:2 compression you need to deliver at least 66MByte/sec.

[Joe_Bez]

OK bit confused now, LOL

As i said the compression seems to drop away with the data rate.
Its dropped to 1.8gb a min last night and the compression went lower than 1.1
(775gb on a 780gb tape)

[Ralf Loehmann_2]

Hello Joe,

it is good to hear that you checked the performance of your array, but what were you able to get to the drive. What were the values of the dev Performance test. I bet is also good, than this would show that the bottleneck is somewhere else. Also with the HPTapePerf test you did you could check how much incoming streams you might be able to handle to have a higher concurency to the drive (you can run multiple instances of it).
I guess than you need to go thru the rest of the document, because it could be system resources or memory or backup application configuration or ... A higher technology tape drive means in the most time newer server, faster disks, maybe more memory, newer backup application version is needed. Check the specification of the autoloader if your configuration is still ok and if so you might need the help of a local consultant.

Only if the device performance test is not
bringing good result you might have hardware issue: http://h20000.www2.hp.com/bizsupport/TechSupport/Document.jsp?objectID=lpg50460#performance

You might also understand why we talk about native data rate, that is what the drive is able to physically can write and if you data is high comprssable you need to deliver much more data. Here some explanation about compression: http://h20000.www2.hp.com/bizsupport/TechSupport/Document.jsp?objectID=lpg50244
Still hope this helps to solve your issue.
Ralf

[Joe_Bez]

Well we had the Unit RMA'ed by HP and a new ones now in.
We updated the Firmware on the SCSI card and put the latest service pack on Backup Exec.

Now we do not see the peaks of 5.5gb/min but we also dont see the lows of 1.8gb/min.
We now see a health consistent 4.5gb and the tapes are showning a 1.4 to 1 compression. :D

Happy now.