StoreEver Tape Storage
cancel
Showing results for 
Search instead for 
Did you mean: 

HP MSL 2024 SCSI 1840 drive throughput

 
SOLVED
Go to solution
Highlighted
Valued Contributor

Re: HP MSL 2024 SCSI 1840 drive throughput

Ken

I did some more testing and managed to get 6.7GB/min maximum.

Are you using arcserve too? I have the default transfer size which is 64K. Is this configurable?
Highlighted
Frequent Advisor

Re: HP MSL 2024 SCSI 1840 drive throughput

Hi CLEB,

I'm currently using Arcserve R15.
This value can be changed depend on each environment. You may need to call up CA support for help to change this value because some other values may change along with MaxSendPacketSize.
Highlighted
Frequent Advisor

Re: HP MSL 2024 SCSI 1840 drive throughput

Hi All,

I've done couple of test with LTT 4.11 Dev perf with latest driver & firmware for LTO4 drive.

With Block mode Fixed ans test size 16 GB. Speed is 177 MB/s for all 2:1, Zero and 1.6:1 compression. (Note: hardware compression is on)

Why I got the same speed for diferent compression? It should be around 120 MB/s for Zero compression and around 240 MB/s for 2:1?

The LTO4 tape that I used for the test is brand new HP tape.

Could someone give me some sugessions what to test more to confirm what is the real maximum speed that my drive can handle.

Thank you so much.
Highlighted
Honored Contributor

Re: HP MSL 2024 SCSI 1840 drive throughput

hi
in the directory log in the storageworksltt path, there should be a file called resultlog, can you attach it here?
the test allow you to test the path between the host and the drive,

if your current througput is limited to 120 MB/s indipendently of what is the compression ratio, that mean this is the max throughput on the path.

the drive can handle 120 MB/s with 1:1 compression ration, and 240 MB/s with 2:1 comp ratio, this because the decompression is made on a chip onboard, before to write phisically on the tape (the max troughput writing on the tape is 120 MB/s due to the motor and tecnology, and this cannot change)

during the test, did you selected the whole tape?
Highlighted
Frequent Advisor

Re: HP MSL 2024 SCSI 1840 drive throughput

Hi Marino,
Thank you for your response.

Attached file is resultlog.ltt

I did select test size is 16 GB, and speed was 177 MB/s for 2:1, 1:1 and 1.6:1 compression.

Do you reckon I need to select full tape for best speed test?

Looking forward to hear from you soon.
Highlighted
Frequent Advisor

Re: HP MSL 2024 SCSI 1840 drive throughput

Hi Marino,

Is there anything interesting from the log?
I disabled hardware compression and did a test again.
This time I got 110 MB/s for all 2:1, 1.6:1 or zero compression. Throughput pretty much the same for test size 16GB, 48GB, 64GB.
Block size and I/O size seems no effect.

Waiting for your comments.
Highlighted
Honored Contributor

Re: HP MSL 2024 SCSI 1840 drive throughput

Hi Ken

I thought I had answered to the question, but something went wrong and my replay is not attached, sorry

From the log I can see that some tapes are marginal, during previous test, the margin in R/W mode was lower then 100%, this is another factor that may influence the throughput

Also I was suggesting to run a test with at least 15 minutes of I/0 in order to get rif of any buffer effect, the tests you runs where 1.30 minutes each

177 MB/s looks to me the max you can acchieve on your SCSI path, from the host to the drive, only way to improve is to try tuning the block size, and also be sure the scsi HBA do not have shared resources with other server components.
You may try to reset the server config to default, or change the slot of SCSI HBA it may be secondary bridged PCI bus (long time I didn't work with server hw, may be nowadays these kind of issue do not exist anymore)

anyway, 177 MBS for the SCSI subsystem is not so bad as it will be hard you can reach the same throughput from the datasource

If you want LTT have also a way to test the data source troughput, the test is "Sys Perf", you can run a Backup performance test, directly on the data you have,
you also have the possibility to create your own data, using the restore performance test, this will allow you to have data you know location and quality/
Highlighted
Frequent Advisor

Re: HP MSL 2024 SCSI 1840 drive throughput

I greatly appriciate your quick response Marino.

I will do more test next week. By the way, my SCSI is ultra320 (320 MB/s) so max throughput on SCSI is much higher than max drive throughput (240 MB/s compress 2:1).

Also I found that the compression ratio in Dev Test option is no meaning with my test. I got 177 with drive compression and 110 without drive compression regardless ratio 2:1, 1.6:1 or zero. Is that correct?

Have a nice wk.
Highlighted
Honored Contributor

Re: HP MSL 2024 SCSI 1840 drive throughput

Several factors may limit the troughput, that may be:
-the server itself: lack of resources, or other task running inbackground
- the phisical layer: the scsi cable, the scsi terminator, the drive scsi interface, any of the components on the scsi chain may be limiting the whole communication.
- traffic congestion: polling for example comming from the host, or other supervisor running on the host (insight agents, or similar) these create traffic on the scsi bus, and the drive should answer to these scsi command causing delay and overhead


you may see a variation of the troughput during test changin the compression ratio when nothing is limiting it, in your case something (as just explained) is limiting.
Highlighted
Frequent Advisor

Re: HP MSL 2024 SCSI 1840 drive throughput

Hi Marino,

I'm back after opening a case with HP.
After checking my support ticket, they found that polling TUR is 10 per second which to much and send me a document how to disable TUR polling.

I applied registy AutoRun = 0 for hplto key, but don't know how to check the TUR. Email back to HP support but not reply yet. I think you may response quicker.

Which tool can I check TUR? After disable autorun, test throughput remains the same.
Thanks.