SUMMARY: DLT capacity

From: Mariel Feder (
Date: Sun Jul 12 1998 - 22:17:24 CDT


>We have a SUN DLT Tape Drive, which is supposedly being able to accomodate
35-70 Gb. We are using DLT tapes type IV.
>I know that 70 is very optimistic, but I think I should be able to get more
than 35.
>However, when I try to backup two directories on two different file
systems, and the tape gives an error message as being full.
> du -sk /edisk1/dir less than 11 Gb
> du -sk /edisk2/dir less than 12 Gb
>As you see, the total is less than 23 Gb.
>I am using the command
> mt -f /dev/rmt/2un rew
> ufsdump 0f machine:/dev/rmt/2un /edisk1/dir
> ufsdump 0f machine:/dev/rmt/2un /edisk2/dir
>What should I do to get the real capacity of this tape?
>I would appreciate your help asap, because it has been a couple of days
already, without being able to backup our database.


It was a hardware problem on the DLT, that was solved after cleaning the
heads of the device. After a lot of checking, we found out that the problem
started the same day we had used the head cleaning tape for the first time.
Another cleaning of the heads, using the same head cleaning solved the
problem. We think it might be that something went wrong on the previous one,
but we don't know what it might be. Now, we are able to backup almost 70 Gb
data no problem.


Thanks for all your replies.
On my question I failed to say that we have a Sun DLT 7000.

Many of you suggested to use a different device name. The right device name
for this hardware is u (for compressed backup) or h (for no compressed):
/dev/rmt/0un or /dev/rmt/0hn (n goes for the no rewind, and 0 might be
substituted by the right target of the device, in my case 2).

Some others, suggested to include a big file size on the ufsdump command (-s
option). However, this is not necessary with this kind of devices. It works
right without it.


Thank to all these people for their fast and helpful answer
Craig Raskin <> (Mr Rene Occelli)
Ray Brownrigg <Ray.Brownrigg@MCS.VUW.AC.NZ>
John Walp <> (James Wendling) (Kurt Werth ph3501) (Brad Young ) (Kelly Fergason)
Ian MacPhedran <Ian_MacPhedran@engr.USask.Ca>
 "Robert L. Bailey" <>
Dennis Martens <>
"Duncan C. White" <>


Mariel Feder - IT Consultant
Meralco Electric Company - MTP - IT.
Phone: (63)(2) 637.8897
Fax: (63)(2) 637.8868

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