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Backup Requires 2 Tapes, Use to Require 1

mwaller14 asked
Last Modified: 2013-12-01
Running the backup with Symantec Backup Exec at work used to require only 1 DLTtape VS1 tape to complete the backup. Lately it has been requiring 2. We use a set up 10 rotating tapes. The tapes have been in use for about 2 years now.

I do notice some Soft Write Errors on each tape (About 12000)  Also about 800 soft read errors

We have about 100GB of data we are trying to backup. Get disk seems to be giving us a different compression ratio. Some 1.19:1, some 1.22:1. Both of these seem low.

What I do not understand is that one day the backup completed with 101400560621 bytes on 1 disk.
The next day the backup requited 2 tapes with 101,362,470,112 (Different tapes).

Is there a way to improve the compression ratio for the tapes, would new tapes fix the problem?

We really do now want to have to purchase a different tape drive is possible.
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Is there any reason why the compression Ratio is not closer to 2:1?
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I am not all hat familiar on the compression of these tapes, but our LTO3 tapes get anywhere from 1.2:1 to 1.8:1 compression, depending on how much data is written to the tapes. Another drive we have, DLT 40/80 only gets from 1.1:1 to 1.2:1. So it may depend on the drive as well. Since you said you do not want to get a new drive then I would suggest buying new tapes. You should also weigh the options of how much is business and data going to grow and would it be worth getting a newer drive with a larger capacity.
ck to see if the tapes that span have the most soft write errors.

get some new tapes, load the cleaning tape a few times before loading the new tapes. Then see if the soft write errors go away.


New tape is supposed to be here today. I wil give it a try tonight.

To do the cleaning, do All I need to do is put the cleaning tape in and it cleans? Or is there something else?
Just put the cleaning tape in and it will clean itself and spit the tape out. Thats all you need to do. Or from Backup Exec you can run a cleaning job and that will reset the statistics on the drive in Backup Exec.


I cleaned the drive and used the new tape last night. Still did not work.

The new tape actually had a worse compression ratio 1.17:1.

Any ideas. Do I have to upgrade the drive to a DLT-4 (which as I have read will be able to put 160GB of data on the same tape as the DLT-VS160 we currently have). to be able to fit it all on one tape? Thanks.
Well, how much do you see your business growing in the next few years? By what amount do you think your amount of data will grow? I would recommend getting an LTO-2 drive at least. It can backup 200/400 GB of data. Also like Dovidmichel said, your compression depends on the data you are backing up. Good luck.


I have talked it over with the office manager. We have decided tp break it down into 2 backups. One file system one night, one the next. Thanks for the help.
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