[CentOS] machine responsiveness with centos 5.1

[Les Mikesell]

Jerry Geis wrote:
> every other day I do full backups to both a second internal disk and an 
> external usb disk.
> 
> I am using a fully up to date centos 5.1 AMD 64 X2 6400+ machine. with 
> SATA disks.
> using an NVIDIA chipset,
> 
> when I do a full rsync the responsiveness of my machine suffers. Slow on 
> the internal disk and really slow on external usb.
> doing "top" shows 0% idle but only 17% CPU usage by the rsync command.
> 
> I am stunned that a 6400+ machine dual core can get this sluggish when 
> doing a copy to disk.
> Is there something I potentially have not set right?
> 
> dmesg shows my SATA disks at UDMA133 and 1.5 Gbps.

Rsync works by transferring the entire directory listing, then wading 
through the whole thing, so there is a certain memory overhead per file 
in the set.  If your file list is huge you might be running out of RAM. 
  Otherwise you are just waiting for the disk heads to seek since they 
won't be where you want them for responsiveness when they are traversing 
the whole disk for comparisons.

-- 
   Les Mikesell
    lesmikesell at gmail.com