dump(8) && -b option

[Roland Smith]

On Mon, Feb 03, 2014 at 08:44:05AM +0100, Matthias Apitz wrote:
> 
> Hello,
> 
> Last weekend I was playing around with the dump options to improve the
> dump speed to my external USB drive. I tried using the -b option to
> increase the blocksize of the written junks:
> 
> # dump -0auL -b 100 -f - /usr 
> ...
>   DUMP: finished in 40 seconds, throughput 7485 KBytes/sec
> 
> # dump -0auL -b 10 -f - /usr
> ...
>   DUMP: finished in 70 seconds, throughput 4274 KBytes/sec
> 
> with -b 1000 the dump hangs forever:
> 
> # dump -0auL -b 1000 -f - /usr
> ...
>   DUMP: dumping (Pass III) [directories]
> (hangs)
> 
> on of its child is doing this where fd 3 is the device to be backed up:
> 
> pread(0x3,0x28809000,0x1000,0x89909000,0xa5,0xbfbfcc88) ERR#5 'Input/output error'
> pread(0x3,0x28809000,0x1000,0x89909000,0xa5,0xbfbfcc88) ERR#5 'Input/output error'
> pread(0x3,0x28809000,0x1000,0x89909000,0xa5,0xbfbfcc88) ERR#5 'Input/output error'
> pread(0x3,0x28809000,0x1000,0x89909000,0xa5,0xbfbfcc88) ERR#5 'Input/output error'
> pread(0x3,0x28809000,0x1000,0x89909000,0xa5,0xbfbfcc88) ERR#5 'Input/output error'
> 
> Why is this?

Input/output error indicates that a file could not be read. Did you run a fsck
before dump?

Are you trying to dump a live filesystem? On 9.0 doing dumps of a live
filesystem that has journaled soft-updates (SU+J) enabled were broken. I am
not sure if this has been fixed already.

> Maybe the best is doing the write to the disk with dd(1), for example
> with
> 
> # dump -0auL -f - /usr  | dd bs=8m > /dev/da0s1a/usr.dmp

For now, the best thing AFAIK is not to use -L but to dump the filesystem from
single user mode when it is not mounted.

Roland
-- 
R.F.Smith                                   http://rsmith.home.xs4all.nl/
[plain text _non-HTML_ PGP/GnuPG encrypted/signed email much appreciated]
pgp: 1A2B 477F 9970 BA3C 2914  B7CE 1277 EFB0 C321 A725 (KeyID: C321A725)
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 196 bytes
Desc: not available
URL: <http://lists.freebsd.org/pipermail/freebsd-questions/attachments/20140203/ffa53a97/attachment.sig>