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Low compression on DAT40

J. Edgar Fennie Jr.
Occasional Visitor

Low compression on DAT40

I am trying to get full compression on my DAT40 internal drive (c5683a) but when I run LLT test with DDS4 tapes my average compression is noted as .8493 in the support ticket, and I get an error message saying the media is not DDS4, although the tape is this type.

I have updated the drive firmware to the lates ersion (v. c305) and I am running the drive on a Windows 2003 Small Business Server. I also have Exec Backup 9.0 installed as my primary back-up program.

The hardware switches are set to ON ON OFF ON ON ON ON ON. (see attached support ticket)

Everything else seems to work fine except I can't get more than 20G on a tape. The data files I am backing up are not compressed. What gives? Any help would be appreciated.
Marino Meloni_1
Honored Contributor

Re: Low compression on DAT40

I had a quick overview at your ticket, and it appear that you are using DDS4, DDS3 and DDS2 cartridges in you unit. So have a double check on what cartridges have been inserted.
another factor is that the unit is asking for cleaning, so ensure you run 5 cleaning cycle with a non expired cleaning cartridge before to make a test.
Last, the compression is highly dependent of the data you are triing to backup, nowadays, lots of OS have already build-in function for otptimization of the file system, so my suggestion is to run L&TT compression test, and see the result, (should be arount 2.1, the test use well-known compressible data), then, still with L&TT you can generate a 35 GB of data with 2:1 compression ration( using prerestore test in system performance), and then backup this well known amount of data to your dds4 with a dds4 cartridge.