tar, mt backup BLOCKSIZES, variable & fixed question Seagate SDT224000N DDS-3 DAT

[Mike Maltese]

> If I run mt blocksize 1024, that sets the actual drive to write data in
> 1024 byte blocks.  If I make an archive with tar with flag -b 20, tar will
> format and send 10,240 byte blocks to the tape drive and the tape drive
> will then subdivide those into 1024 byte blocks and put them onto the

According to the tar manual, you should use a blocking factor that suits the
average file size in the archive. It also says that tape and cartridge media
likes larger blocking factors, as it will give better throughput and
minimize tape and head wear. I use 128 with my DDS2 drive. Also, 20 is the
default, so if that's what you want to use you don't need to specify it.

Have a look here for more info:
http://www.gnu.org/software/tar/manual/html_node/tar_132.html