MSL5026 expected throughput?

[Niklas Andersson_1]

Hi!

I'm wondering which throughputs I could expect from the MSL5026 Library with one 40/80 DLT Tape drive?
Server is DL360 1400MHz 1gig RAM and W2K server SP4.
Network is switched 100Mb/s.
The company has a large amount of data and the backups take way too long, as of now I'm getting a throughput of around 150-200MB/min both local and LAN (which is ~3MB/s and the library should be able to do 6 according to HP).
Backup software is ArcServe 9.

Sincerely

Niklas Andersson

[Marino Meloni_1]

n very usefull function is part of L&TT, this function allow you to troubleshoot the throughput problems with Tape devices.

you have to select device performance to send data from the server memory to the scsi device, this test will allow you to determine if there is some problem on the scsi chain\
you have also system performance, that allow you to know if the problem come from your local disk, or software. this test will read (or write) data from disk to the server memory and calculate.

The higher level rate specifyed for a Tape device, is usualy related to a compression ratio, higher is the ratio, higher is the throughput, because this data is calculated on the server, that's why usualy we need to refer to native value.

[Niklas Andersson_1]

Ok, thanks for the tips. I will check out the L&TT software and get back after that.

So 6MB/s is for 2:1 compression? Compression on my drive is about 1,4:1 so i shouldn't expect more then ~4,2MB/s?

[Niklas Andersson_1]

Hi again!

Now i tested the L&TT and the results were:
Writing 4GB to tape at compression 1,6:1
2MB/s
Read from local disk (5min)
12MB/s
Read from network (5min)
5MB/s

Some more info:

Drive FirmWare:
installed V080, newest V086
Library FirmWare:
installed 0.421, newest 0.423
Controller:
Compaq 64-bit/66MHz Dual Channel Wide Ultra3 SCSI (adpu160m.sys)
installed ver. 6.1.640.100 newest ver. 6.1.645.100

Device Analysis:
Device Analysis completed; no problems found, but abnormal conditions detected.

Device self test passes without any problems

[Curtis Ballard]

Try running the "device assessment test" or "acceptance test" on the tape drive. The name depends on the LTT version you are using. "acceptance test" was confusing to some people so the name was changed.

This test is a read/write test so it will require a scratch tape. The test is almost exactly the same thing that would be run in the factory to determine what needed repaired if the drive was returned. If the drive passes it is functioning within normal field tolerances. If it is functioning within normal field tolerances it should be able to run faster than 2MB/s.

Another test to run is try testing with 3:1 compressable data and see if the transfer rate improves. It should if the problem is with the rate the tape drive is writing data.

[Niklas Andersson_1]

I ran the DLT Acceptancy Test.
Got no errors, Observe that the tape was in the drive the whole time (long way from office to drive =P )
Attaching the LTT-file.

[Niklas Andersson_1]

Sorry for the many posts!

I have now run the Device Performance test with compression 3:1, the results:
4096 MB written in 776 seconds at 5 MB/s

Sincerely

Niklas Andersson