dump reads more than restore writes?
Dan Nelson
dnelson at allantgroup.com
Mon Jan 8 03:42:16 UTC 2007
In the last episode (Jan 07), David Gilbert said:
> I've got a command line like the following:
>
> dump -0af - /dev/ad1s1g | restore -rf -
>
> ... and I'm watching gstat. ad1s1g is not mounted. The disk on which
> the restore is running is also quiet (nobody using the disk).
>
> And gstat says that ad1 is consistently reading 31 to 37 megabytes
> per second and ad2 (the restore disk) is consistently writing 10 to
> 13 megabytes per second. This is over hours --- the figures never
> catch up.
If you have a lot of small files, dump may be rereading directory
information. Dump has a cache option that can help, but make sure you
also dump a snapshot (i.e. always use -L when using -C).
--
Dan Nelson
dnelson at allantgroup.com
More information about the freebsd-hackers
mailing list