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Problems with Hardware Compression C1537A DDS3

Andi_2
Occasional Visitor

Problems with Hardware Compression C1537A DDS3

Hi,

i??ve got a problem with hardware compression on my C1537A.
Hardware Compression oin the drive is enabled but the drive??s storing max. 11GB on my DDS3 Tape with a max write rate of 60mb/min. Why is the rate less data than the native amount of the drive ?

Any Idea ?

I use ArcServe 2000 SP3 on a Win2k Server SP2, the SCSI Controller is an Adaptec AIC7880 UW (also tried with an Adaptec Ultra160)

no
3 REPLIES
Vincent Farrugia
Honored Contributor

Re: Problems with Hardware Compression C1537A DDS3

Hello,

How did you set the switches 1 and 2 (controlling compression)?

Switch 1 should be set to 1 to enable compression. Switch 2 should be set to 1 as well for Host control.

HTH,
Vince
Tape Drives RULE!!!
Marino Meloni_1
Honored Contributor

Re: Problems with Hardware Compression C1537A DDS3

hi
-Conpression of data depend of the data itself, now a days, the data on a server are already optimized and have a low ratio in compression, you can check this, with an utility like winzip, that use a software algoritm to compress data, then compare your data with the result of winzip plus 5 - 10 % value (because Backup Software ad some header and catalogs on the tape).
-Another thing that can create problem is if you have enabled the software conpression, then the data will be sent to the DAT already compressed, then no more compression allowed.
-If you have an old tape or a head problem on your dat, this can worst space due to bad blocks.
-The transfer rate is right, about one Mb/sec id the commom transfer rate for a DDS3 Tape Device.

bye

marino
harry d brown jr
Honored Contributor

Re: Problems with Hardware Compression C1537A DDS3

Andi,

If you are writing uncompressable files they will actually take up more room on the tape than if you didn't compress the files.

A DDS-3 tape can store 24GB of data PROVIDING it can be COMPRESSED into 12GB.

this means the tape can only really store 12GB!

live free or die
harry
Live Free or Die