Re: Q: 2.4.[37]-XFS: /dev/nst0m: cannot allocate memory

From: Albrecht Jacobs (Albrecht.Jacobs@janglednerves.com)
Date: Sun Aug 19 2001 - 13:59:47 EST

Kai Makisara wrote:
>
> On Fri, 17 Aug 2001, (Martin Jacobs) wrote:
>
> > Hi all,
> >
> > I cannot read anything from my tape (Tandberg DLT8000, LVD
> > interface, ID=5) connected to an aic7899 or an sym53c895 using
> > kernel 2.4.3-XFS or 2.4.7-XFS. (Everything works fine on
> > 2.2.16.) Loading of st.o works. stinit works. mt (status, tape
> > positioning) works. But when I try to read the amanda header
> > from the tape (dd if=/dev/nst0m bs=32k count=1) I get the
> > error
> >
> > dd: reading `/dev/nst0m': Cannot allocate memory
> >
> ...
> > Nearly the same for tar (with default block size of 512 byte).
> >
> > BUT: if I use bs=64k it works!!?
> >
> In variable block mode in 2.4, you get ENOMEM if the block on the tape is
> larger than the byte count in the read(). 2.2 just returned what you asked
> for and silentlry threw away the rest of the block. If the byte count is
> larger than the block size, then the block is returned.
>
> I.e., the first block on your tape is larger than 32 kB.
>
> Kai

If I understand you right this is a FEATURE, not a bug! I find it quite
irritating when using a tape device. Shouldn't I get some error message
about wrong block size?
        Forgive me but I am some sort of end user (admin) and not a kernel
hacker.
BTW, where can I get documentation about this 'feature'?
 
Thanks anyway! 

-- 
albrecht jacobs

jangled nerves gmbh
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This archive was generated by hypermail 2b29 : Thu Aug 23 2001 - 21:00:31 EST