/dev/nst0: Permission denied

Wed Sep 5 05:14:00 GMT 2001

On Wed, Sep 05, 2001 at 01:02:51PM +0100, Mark Himsley wrote:
> Hi,
>> I have a tape device problem. I'm running on Win2K pro SP1 + all M$
> recommended patches and I've just installed the latest Cygwin.
>> I mounted the DAT drive with
>> mount -s -f -b //./tape0 /dev/nst0
>> and it seems to be working, I can write to a DAT and read the data back.
>> BUT, if I put in a tape I wrote on Linux I get the following:
>> $ cat /dev/nst0
> cat: /dev/nst0: Permission denied
>> Why is this, and how can I read the DAT tape.

Wrong blocksize. Call `mt -f /dev/nst0 status 2' with tape in
drive. It will show you the blocksize currently set in the
NT tape device driver (often 512), e.g.:
$ mt -f /dev/nst0 status 2
tape capacity : 1953251 KB remaining : 1953251 KB
current block : 0 write protected : no datcompression : on
min block size : 1 max block size : 65536
def block size : 16384 cur block size : 512
report setmarks : off 
The current blocksize is obviously reported in `cur block size'.
To get rid of that you either have to know the blocksize which
is used when the tape has been written by Linux (probably 5120)
$ mt -f /dev/nst0 setblk 5120
or you set your tape device driver to `variable block length'
which let the device drive figure out the size of the next
block on the tape by itself:
$ mt -f /dev/nst0 setblk 0
Note that not all device drivers are able to deal with variable
block size. Howver, the standard DAT driver on NT (4mmdat.sys)
is able to do that.
Corinna
-- 
Corinna Vinschen Please, send mails regarding Cygwin to
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