Dump size with ufsdump

Hi Experts !

over years i have done backups with ufsdump. My actual problem is the following:

A certain batch with ufsdump reach tape end. It copies aprox. 15Gb of data when the end of tape is reached. Another ufsdump job runs well and copies up to 19Gb.

So my question: what could be the diference:

1. I try diferent brands of tape. I use the same tape for the 15Gb (it stops then) and later for the 19Gb backup (and it finished well).
2. The 15Gb has not significant more files or directories than the 19Gb (and 4Gb of directory information should be too much).

Environment: SunFire V250, Solaris 8, HP ShureStore Dat24 external, DDS3 dat cartridge

Thank you very much,
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You mention batches... are the commands used exactly the same?

Is it possible to post the actual command line or lines being used?
I suppose it's a question of how well the data can be compressed. To check: Do both dumps into a file, compress the two files (i.e. sig gzip) and then compare sizes.
adminpeterAuthor Commented:
Thank you for your response.

About the batch: Here are the lines (changing real file names):

# batch #1

mt rewind
ufsdump  0cf /dev/rmt/0cbn /u2/users
mt rewind
mt offline

# batch #2
mt rewind
ufsdump 0cf /dev/rmt/0cbn /u1/users
ufsdump 0cf /dev/rmt/0cbn /u2/users2
ufsdump 0cf /dev/rmt/0cbn /u3/users
ufsdump 0cf /dev/rmt/0cbn /u4/db
mt rewind
mt offline

About compression:
Where is the diference. The ShureTape will save 24Gb compressed anyway. The -S option in ufsdump gives following info:
> ufsdump 0cSf /dev/rmt/0cbn /u2/users/files1
And this is the size that needs the backup and it should fit on a 24Gb ?

About compression: Your Tape (DAT24) can really store 12GB of data. With a normal (average) compression rate you get those 24GB. If however on the partition you want to save there are only gzipped files then there are already compressed very well, and therefore you can only store 12GB of those. If on the other hand, you did only store textfiles on those partitions then those can be compressed down to maybe 20% of the original size, so you could be able to store as much as 60GB of textfiles.

About your batches: you specify the option "b" which is for blocking factor but you dont specify a blocking factor. Is there a reason for doing this, specially because by using the cardridge-option "c" you already defined the blocking factor to be 126 blocks per write ?

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adminpeterAuthor Commented:
Hi neteducation,

you should be right. The problematic partion contains now Autocad (Inventor 10) files. They may be in a pre-compressed format or hard to compress anyway.

Concerning the batch parameters they are historical and i will adjust them.

Thank you so far, bye, Peter.
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