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DLT Tape not seeing full capacity in Backup Exec 11D

Posted on 2008-11-12
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Have 320Gb tapes, but max capacity I'm seeing of some new tapes is 98Gb

Max capacity I'm seeing of any tape is 149 Gb

Tape Storage Unit is a HP StorageWorks MSL 5000 (Firmware version 520) - the drive itself is a Compaq SDLT320 (Firmware version V095/CPQ-2) - Both firmware versions are latest available.

Looking to get 320Gb out of my tapes!
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Question by:ivan_sanders
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by:karwak
ID: 22949558
SDLT means 160GB native / 320GB compressed....

Have a look at this article http://en.wikipedia.org/wiki/Digital_Linear_Tape . This one may help you to understand about the full capacity available...
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by:LTO_Moe
ID: 22951758
I think it could be a number of possibilities.

1.  The data you are backing up may not be compressible.  However, you should still be getting very close to the 160GB mark for each tape.

2.  You could have a bad batch of media.  It doesn't happen very often, but it does happen.

3.  You could have a bad or dirty head on the tape drive.  If you can, listen to the drive as it is backing up to see if the drive is "shoeshining" (stopping, backing up, then starting again).  Bad media would also cause this behavior.

4.  The drive may not be running in compressed mode.  Could be problem with drive or simply configuration error.

It may be a combination of the above.

There are two free programs you can download to run tests on the tape drive and media.  The first is Quantum xTalk (quantum.com) and the second is HP Library & Tape Tools (hp.com).  xTalk gives more specific and detailed information in the tests.  WARNING:  Most of the tests will overwrite any data on the tapes, so use media that doesn't have any data you want to keep.
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by:TapeDude
ID: 22965032
++ LTO Moe.

Also... check the device block size. Using small block sizes can reduce tape capacity considerably (as well as making i/o a LOT slower). It should be set to 64k.

To do this, click the Devices tab, right click the drive, select properties, and click the configuration tab.

If you increase the block size make sure the buffer size is at least as large (this won't effect capacity, it's for performance reasons)

And, while you're there, do make sure "Enable compression" is selected!
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by:ivan_sanders
ID: 22973433
Yes, just checked - block size and buffer size both already at 64k and compression is on..
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by:ivan_sanders
ID: 22973446
Compression is working ok I think - various compression ratios shown between 4.85 and 1.11

All tapes now showing 'x of 149 Gb' (used capacity)
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by:TapeDude
ID: 22974837
Then your next step is to listen out for 'shoe shining' - the tape drive repeatedly stopping/starting/reversing, which will either indicate a dirty or worn/damaged head. If a couple of cleaning cycles doesn't fix this then either it's bad media, or time for drive refurbishment.
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by:ivan_sanders
ID: 22980914
Thanks for that - but no hope of hearing anything! - I lay on the ground but the noise from all the other servers is just way too loud - no other place (logs) I can look at??
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by:TapeDude
ID: 22981048
At this stage you should be giving Quantum's DLT Sage / Xtalk (now called "StorageCare Sage xTalk Management Console") a shot:

      http://www.quantum.com/ServiceandSupport/SoftwareandDocumentationDownloads/SDLT320/Index.aspx
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Author Comment

by:ivan_sanders
ID: 22990641
Mmmm - having some problems now!   Backup Exec still works ok.   Xtalk won't work - says that I've got a scsi termination problem - but HP Storage Works Library and Tape Tools works ok - Running the test through that tool gives the following errors:

|__ Test 'SDLT Drive Assessment Test' started on device 'COMPAQ SDLT320' at address '5/0.5.0'
    |__ CAUTION: any data on the loaded cartridge will be lost. Continue with the test?
    |__ Failed
    |__ Analysis Results
    |    |__ SDLT acceptance test version V02.02.2007
    |    |__ Time: Wed Nov 19 11:17:11 2008       Serial Number: MYJ05027PY
    |    |__ Firmware rev 'V095' is up-to-date for 'COMPAQ SDLT320' as of 1161025200.
    |    |__ events seen as a warning (from prior to this test)
    |    |__ Packet # 24 - Event: A508 [V95-0 10-Oct-2006] 967:46:24.865 POH/PC= 27449/51
 Temp= 44 (38,-128,-128) Motion (Hr:Min) = 1180:10
       0F200F02 03100310 0000202B 0003210F 00000000 D1EE6C74 2128A69C 00000000
       00001000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
       00000000 00000000 00000000 00000000
 
    |    |__ Packet # 25 - Event: A508 [V95-0 10-Oct-2006] 1014:50:37.693 POH/PC= 27496/51
 Temp= 44 (38,-128,-128) Motion (Hr:Min) = 1204:30
       0F200F02 03100310 0000202B 0003000F 00000000 D1EE6C74 2128A430 00000000
       00001000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
       00000000 00000000 00000000 00000000

    |    |__ Packet # 26 - Event: A503 [V95-0 10-Oct-2006] 1014:54:37.647 POH/PC= 27496/51
 Temp= 44 (38,-128,-128) Motion (Hr:Min) = 1204:30
       200E0001 00068000 00AB0000 00000001 00000000 00060000 EB72FFFF 01000001
       00100000 00000000 00100000 0E100640 00A20068 098C0000 2B950000 04B4FFF0
       FFFA0000 00000000 00000000 00000000

    |    |__ Packet # 30 - Event: A512 [V95-0 10-Oct-2006] 117:39:43.630 POH/PC= 27615/52
 Temp= 45 (39,-128,-128) Motion (Hr:Min) = 1225:20
       0114FC00 00000000 6BDF1227 A30898DF 048000A5 556572F7 75390F05 1E002710
       57A30284 00BE0000 00000000 00000000 00000000 00000000 A30898DF BBE40E22
       00000036 0000006F 00000000 00000000
 
    |    |__ correctable write error uniformity data
    |    |__ section 4 raw write errors: 786
    |    |__ section 3 raw write errors: 673
    |    |__ section 1 raw write errors: 483
    |    |__ section 2 raw write errors: 474
    |    |__ section 8 raw write errors: 397
    |    |__ section 7 raw write errors: 389
    |    |__ section 6 raw write errors: 319
    |    |__ section 5 raw write errors: 283
    |    |__ Error rate test parameter values for write
    |    |__ uncorrectable write errors: 0 (limit is 0)

    |    |__ total raw write errors: 3885 (limit is 11062)

    |    |__ total write bytes processed: 7450 MB

    |    |__ Error rate test parameter values for read
    |    |__ uncorrectable read errors: 0 (limit is 0)

    |    |__ total raw read errors: 8358 (limit is 885)

    |    |__ total read bytes processed: 7399 MB

    |    |__ Total raw read errors (8358) exceeded threshold value (885)
    |__ Operations Log
        |__
        |__
        |__ executing SCSI interconnect test...
        |__ executing firmware revision check...
        |__ executing event log check...
        |__ executing read...
        |__ executing read/write criteria check...
        |__ executing quick write/read test...
        |__ executing quick write/read test...
        |__ executing quick write/read test...
        |__ executing quick write/read test...
        |__ executing quick write/read test...
        |__ executing quick write/read test...
        |__ executing write/read minimum block size test...
        |__ executing write/read minimum block size test...
        |__ executing write/read minimum block size test ...
        |__ executing diag self-test...
        |__ executing bug check 8008 test...
        |__ executing bug check 8008 test...
        |__ executing write/read pattern5 test...
        |__ executing write/read pattern5 test...
        |__ executing write/read pattern4 test...
        |__ executing write/read pattern4 test...
        |__ executing write/read pattern3 test...
        |__ executing write/read pattern3 test...
        |__ executing write/read pattern2...
        |__ executing write/read pattern2 test...
        |__ executing write/read pattern1 test...
        |__ executing write/read pattern1 test...
        |__ executing write/read pattern0 test...
        |__ executing write/read pattern0 test...
        |__ executing error-rate test...
        |__ executing error-rate test (write)...
        |__ executing error-rate test (read)...
        |__ executing error-rate test...
        |__ writing additional data...
        |__ reading additional data...
        |__ Test failed
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Expert Comment

by:TapeDude
ID: 22990917
All these write errors suggest either i) dirty head (ie, run a cleaning cycle) or ii) bad/old media or iiii) worn or damaged write head or write bias incorrect / write circuitry malfunction.

have you i) tried cleaning the drive head with a cleaning cartridge, ii) new media?
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Author Comment

by:ivan_sanders
ID: 22990936
yes, I run a cleaning cycle once per week and haven't had any errors - when I look at the tape properties there are zero erros (seek, read, write etc)

The test above was with a new tape.
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Accepted Solution

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TapeDude earned 2000 total points
ID: 22990980
The fact that xtalk is telling you you've got a termination problem should ring alarm bells. Have you tried a different cable and terminator?

However, the above should not make a difference to the number of write errors generated. Assuming you've been using a fresh cleaning cartridge (they only last 20 cycles), at this stage I think you have to face up to having a faulty drive.

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