dlt_IV - media request after 30gb

[mykill]

hi all,

using w2003 - backupexec 9.0 - tandberg dlt 8800 - dlt iv tapes.

on SOME backup jobs the software requests for a 2nd media, although the tape's capacity is not reached (sometimes at about 30gb, sometimes at about 20gb).

this is strange because :
- i erased the tape before
- i do not use hardware compression
- the backup is always set to "overwrite" media
- backupexec indicates available tape capacity 37.5gb

i'm using dlt iv tapes. am i right that ALL dlt iv tapes have a 40gb (37.5) native capacity?

thx in advance for any help on this.

my_kill

 

[SteelBurner]

hi my_kill,

you are right, DLT IV has a capacity of 40gb native and up to 80gb compressed, but that depends very much on what you back up (i.e. many JPEGs or lots of txt-files).
I suggest to use hardware compression - the tape drive controls this. For my environment it gives the best result.

HTH,
SteelBurner

 

[comtec17]

If you backup a ton of small files, for example 20k, you are still using 1 - 32k block for the backup of that file. This will reduce the capacity of tape being utilized. Never count on compressed rates as most of the time you will never get them.