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DAT40 can't compress on W2K Svr

William Yan
Occasional Visitor

DAT40 can't compress on W2K Svr

i have a DAT40 drive with Adaptec SCIS adapter on a W2k Svr. I am using Ntbackup of daily backup. i have a little problem that i just cannot use the hardware compression function.

i use script for daily backup and have the switch /hc set to on, but i find the Ntbbackup just do not use compression and the result is i cannot backup all the data over 20GB. After 20GB of backup, the drive just eject the tape and i need to replace a new one.

Also the Ntbackup sometime do not do the backup as scheduled every night for no reason. It seems that if there are some media already exist in the tape, the Ntbackup just cannot start the backup, and i need to erase the tape manually before hand.

Any reason for that and what is the proper way to do a backup on W2k?

Many thanks for all input.
Eugeny Brychkov
Honored Contributor

Re: DAT40 can't compress on W2K Svr

please install HP Library and Tape Tools from , generate support ticket and find if drive's hardware compression is turned on (there's a switch at the bottom to enable/disable drive's hw compression). Please note that drive will be able to backup 40GB of data only with compression ratio 2:1. If you back up already packed files (multimedia, archives, etc) then ratio will be approx 1:1 and drive will be able to backup only 20GB. Also please make sure that you have compression turned on only at one location - on the drive (dip-switch, hw compression) or in backup utility (software compression)
About NTbackup issues - try analyzing drive by LTT, updating its firmware
Jesus Aguirre Rasco
Occasional Visitor

Re: DAT40 can't compress on W2K Svr

I've got the same problem. I do de test with the last Library and it's said me that te ratio it's 1:2'31 but when i do a backup with ntbackup it stop at 20Gb. I use varius tapes of 20/40Gb anf i select de check of "hardware compress". The data it's normal data it isn't video and compress data , i know that the do´nt arrive to 1:2'31 but i think that it must compress more that 1:1.