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Re: [rdiff-backup-users] slow incrementals over ssh to localhost
From: |
Jeff Strunk |
Subject: |
Re: [rdiff-backup-users] slow incrementals over ssh to localhost |
Date: |
Thu, 8 Mar 2007 10:41:01 -0600 |
User-agent: |
KMail/1.9.5 |
On Thursday 08 March 2007 10:38 am, Randall Nortman wrote:
> On Thu, Mar 08, 2007 at 09:59:20AM -0600, Jeff Strunk wrote:
> > I just found that it takes 3 times longer to perform an incremental
> > backup via ssh of the local machine than to perform the incremental
> > backup directly.
>
> [...]
>
> It is most likely due to the CPU overhead of encrypting and decrypting
> (and possibly compressing/uncompressing) byte of data that needs to be
> "transferred". In fact, ssh to localhost can be slower than ssh to
> another on the local network, because the CPU load is split between
> the two machines. Given that rdiff-backup is a bit of a CPU hog on
> its own, adding the compress/encrypt/decrypt/uncompress overhead is
> likely to peg your CPU usage at 100%. Check this while you're running
> the backup to confirm. You are either CPU-bound or I/O-bound, and I
> suspect it's CPU.
CPU bound would be it. Thanks.