dump faster from remote than from local
Don Lewis
truckman at FreeBSD.org
Sun Oct 5 12:55:57 PDT 2003
On 5 Oct, Randy Bush wrote:
> 4.9rc of yesterday
>
> dump from B->A i.e. from a system on local ether
>
> DUMP: DUMP: 2082890 tape blocks on 1 volume
> DUMP: finished in 478 seconds, throughput 4357 KBytes/sec
> ^^^^^^^^^^^^^^^
> and a local dump on A
>
> DUMP: DUMP: 3560987 tape blocks on 1 volume
> DUMP: finished in 3694 seconds, throughput 963 KBytes/sec
> ^^^^^^^^^^^^^^
> why is local slower than remote?
What are you dumping to on A? If you are dumping to a file on the same
spindle, you spend a lot more time doing long seeks. Is there other I/O
occuring on the same spindle as the filesystem that you are dumping on
A?
Could the file system on B have a small number of large files while A
has a large number of small files? Has the file system on A been run in
a near-full condition for a long period of time so that there are a lot
of disk blocks that are poorly placed? What results do you get if you
dump each file system to /dev/null on the local machine?
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