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Hardware compression not working on ultrium 448

matt.ostiguy
Occasional Visitor

Hardware compression not working on ultrium 448

I do have a open case with CA, but this is starting to drive me nuts.

CA Arcserve 11.5, with the latest device update installed (just about the only download available for it)
Win2k3 SP1
HP ultrium 448 in the 1U rack unit, with HP scsi cable and HP u320 scsi card.
I am running the 1.0.3.1 driver for the Ultrium drive, the most recent I could find. I had been running 1.0.2, but it did not make a difference.


Arcserve 11.5 says hardware compression is enabled by default, but my backup jobs were not getting any compression at all. So I have been playing with a test backup job of IIS logs (text files), and it seems that hardware compression simply is not working. When I manually disable HW compression, and enable SW compression on the job, the result is 48MB backed up, 3.06MB on the tape, which correlates with the insanely high compression ratio Windows generated when I zipped up those files (the .zip was under 2MB). Using all the defaults (which is HW compression), it is roughly 48MB backed up to 48MB of tape used.

HP's tape tools thing passes everything with flying colors - on the test that says if you get less than 2:1 compression, I got 2.6:1.

So, is there any chance that this is a hardware issue, or is this a bug with CA? At the hardware level, what goes on - is it a SCSI command that toggles on HW compression?

Any insight appreciated.

5 REPLIES
David Ruska
Honored Contributor

Re: Hardware compression not working on ultrium 448

> So, is there any chance that this is a hardware issue, or is this a bug with CA?

The LTT compression test verified the device would compress data, if hardware compression was enabled, and using known (compressible) data patterns from LTT.

You can check fairly easily to see if your backup tape was written with compression, and what the compression ratio was.

Load your backup tape, and then run the LTT "media analysis" test. Before starting it, you can select the options, and change "amount of data read in each phase", if the backup is >>200MB.

After the test, look under the test results tab. It will list the compression ratio. If it's exactly 1.00, then compression was likely disabled (not 100.00% accurate, as there's a small chance compression was on, and the compression averaged out to 1.00).

> At the hardware level, what goes on - is it a SCSI command that toggles on HW compression?

Basically, yes. There's a SCSI "Mode Select" command sent to the drive to control compression. Within the mode select command is a "Data Compresssion Characteristics" page, and within that is a "DCE" bit (data compression enable) for writes, and a write compression algorithm ID (for which the LTO drive only supports one - ID 1).

There's a SCSI "Mode Sense" command to read back most of the Mode Select settings, but there's no quick utility I know of that does that for you.
The journey IS the reward.
Mato_1
Occasional Visitor

Re: Hardware compression not working on ultrium 448

I have same problem. Same HP Ultrium 448 (1U rack unit), SCSI card HP 64-bit/133-MHz pci-x dual channel ultra320 HBA(LSI Logic 1020/1030 Ultra320). I have ARCserve 9.01 with latest SP.

My real scheduled job (full backup 220 GB, increment 40GB) have compression ratio 1.00.

When I start test job (10GB) (RUN NOW) then there is compression ratio for example 1.1

Wim van Laarhoven
Occasional Visitor

Re: Hardware compression not working on ultrium 448

Did someone got an update for this?
I have a HP Surestore Ultrium II, and also 0% compression.

did not open a case at CA just jet, but guess I have to do that.

Any reply is welcome.
Satish M.S.
Valued Contributor

Re: Hardware compression not working on ultrium 448

I am not sure if this is of any help.
Sometime back there was a similar issue (althought not pertaining to compression as such) with respect to slow throughput for DLT drives using BrightStor as the backup app.

The following fix worked:

stop the "CA Brightstor Tape Engine" service and locate the following registry folder with regedt32.exe; "HKLM/Software/Computer Associates/Brightstor ARCserve Backup/Base/TapeEngine/DEVICE#/" -look "Info" value for which device# is your dlt has-, then ADD DWORD value

data type= Reg_Dword
valuename= DefaultBlockFactor
data= 7, Hex.

then start the "CA Brightstor Tape Engine service" and back-up your files :)

After the fix the backup speed pretty much increased to 200 MB/minute

Satish
Wim van Laarhoven
Occasional Visitor

Re: Hardware compression not working on ultrium 448

well, to anyone who still cares about this one.
installing SP1 for 11.5 with device upgrade pack 5 fixed the compression issue.
No registry settings where required to get full speed from the LTO drive.

http://supportconnect.ca.com/sc/redir.jsp?reqPage=search&searchID=QO77091
(SP1)

http://supportconnect.ca.com/sc/redir.jsp?reqPage=search&searchID=QO78909
(Device Support Update 5)