Backup problem

[Fadia Almarei]

Dear All

I have Ultinum tape drive directly connected Dell power edge 2850 server with redhat enterprise AS v.4 , the backup operation is very slow, backup 27GB data took 10 hours which is seems to be incorrect , what sould i check to solve this problem

[Ivan Ferreira]

What are you backing up? A lot of very small files could take more time that one big file.

What is the backup software that you are using? What is the block size used?

You can try backing up test data using:

time dd if=/dev/zero of=/dev/st0 bs=256k count=4096

[Fadia Almarei]

I usr tar command for backup , i use the default block size , i try to backup one large file (2GB) and it took half an hour and backup number of files with total size of 27GB and it took 6 hours.

[Florian Heigl (new acc)]

the default blocksize (512bytes I guess) might hurt performance, but I'm not sure if to that extent; still, try raising it to 64kish...