badblocks blocksize setting

badblocks blocksize setting

[Marius Reiner]

Hi,
not really a reiserfs issue:
When following the FAQ everything is fine, I set blocksize zu 4096 as
debugreiserfs told me, and don't get any bad blocks.
Nevertheless I'm a bit concerned about the ones, badblocks reports, when
being invoked without the -b option. How does this happen?
Which docs are there on this topic apart from badblocks manpage/sourcecode?
Or should I just ignore them?
Thanks in advance
Marius

Re: badblocks blocksize setting

[Oleg Drokin]

Hello!

On Sat, Mar 15, 2003 at 01:09:19AM +0100, Marius Reiner wrote:

> not really a reiserfs issue:
> When following the FAQ everything is fine, I set blocksize zu 4096 as
> debugreiserfs told me, and don't get any bad blocks.

Good.

> Nevertheless I'm a bit concerned about the ones, badblocks reports, when
> being invoked without the -b option. How does this happen?

Can you please show the command line and the resulting output with badblocks?
Also what is in dmesg output after such a run?

> Or should I just ignore them?

There is not enough info yet.
Can you please tell us whole story?

Bye,
    Oleg

Re: badblocks blocksize setting

[Marius Reiner]

> Hello!
>
> On Sat, Mar 15, 2003 at 01:09:19AM +0100, Marius Reiner wrote:
>
> > not really a reiserfs issue:
> > When following the FAQ everything is fine, I set blocksize zu 4096 as
> > debugreiserfs told me, and don't get any bad blocks.
>
> Good.
>
> > Nevertheless I'm a bit concerned about the ones, badblocks reports, when
> > being invoked without the -b option. How does this happen?
>
> Can you please show the command line and the resulting output with
badblocks?
> Also what is in dmesg output after such a run?

# badblocks /dev/hdc8 -b 4096
# dmesg -c
invalidate: busy buffer
# badblocks /dev/hdc8
979932
# dmesg
invalidate: busy buffer
attempt to access beyond end of device
16:08: rw=0, want=979936, limit=979933
attempt to access beyond end of device
16:08: rw=0, want=979936, limit=979933

So using the -b option has the side-effect of not accessing the partition
beyond its end? I'm running a vanilla 2.4.20 kernel, actually it's the
kernels task to refuse those accesses, isn't it?
However, what I'm missing in the FAQ, is a short note about _why_ one should
use the -b option, so no worries arise when getting bad blocks without it.
Thanks
Marius

Re: badblocks blocksize setting

[Oleg Drokin]

Hello!

On Sat, Mar 15, 2003 at 12:38:23PM +0100, Marius Reiner wrote:

> > Can you please show the command line and the resulting output with
> badblocks?
> > Also what is in dmesg output after such a run?
> # badblocks /dev/hdc8 -b 4096
> # dmesg -c
> invalidate: busy buffer
> # badblocks /dev/hdc8
> 979932
> # dmesg
> invalidate: busy buffer
> attempt to access beyond end of device
> 16:08: rw=0, want=979936, limit=979933
> attempt to access beyond end of device
> 16:08: rw=0, want=979936, limit=979933

Hm, is 979936 looks like size of your device in kilobytes (+-3)?
If so, this is known kernel bug/problem, where it cannot access parts
of device at the end sometimes. This is somehow related to setblocksize.
This can be ignored, then.

> However, what I'm missing in the FAQ, is a short note about _why_ one should
> use the -b option, so no worries arise when getting bad blocks without it.

-b is needed so block output by bad blocks have the same bad blocks as
in reiserfs. (4096 bytes in size, without -b, badblocks
defaults to 1024 bytes blocks, so you need to divide its output by 4).

Bye,
    Oleg