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

[Dan Nelson]

In the last episode (Dec 12), Jonathan Wright said:
> up" if there is a delay in the host computer's data access.  However,
> I am getting inconsistent information on the variable blocksize
> setting in mt and don't know if I should use it or not.  One site I
> found said that variable blocksizes allow the drive to write blocks
> at a size that it thinks will be best for the data speed at hand,
> while another site said that it allows the drive to use the blocksize
> being sent to it from the backup application (making 10,240 byte
> blocks in the above tar example).  Who is right, or have I got this
> all mess up? :)

variable blocksize means write data to tape using whatever size chunks
the user write()s.  I think only ancient QIC tapes actually need you to
set a fixed blocksize via mt.

> Also is there a preferred blocksize for DDS-3 DAT drives?

I use 64k for everything.

-- 
	Dan Nelson
	dnelson at allantgroup.com