[Gllug] External hard disks

[Daniel P. Berrange]

On Mon, Jan 30, 2006 at 02:43:09AM +0000, Nix wrote:
> On Sun, 29 Jan 2006, Daniel P. Berrange prattled cheerily:
> > On Sat, Jan 28, 2006 at 06:02:32PM +0000, Jack Bertram wrote:
> >> If I did this, presumably I could still use smartd to monitor it (over
> >> usb?) and include it in volume groups (using LVM2) but swapping it
> >> in/out when it failed would be much easier, and more hotpluggable.  I'd
> >> also be able to lock it away - altogether much more flexible.
> >> 
> >> Anyone got any experience with using one of these or can tell me
> >> whether they foresee any problems, with:
> >> - speed compared to SATA (doesn't have to be rocket speed, just hold
> >>   films, music, etc.)
> > 
> > Yeah, with USB-2 speed is not an issue.
> 
> CPU overhead is, though. It's at least as expensive as PIO-mode disk
> access.

I've really not had any problems with CPU overhead - I frequently create
& update multiple-GB files to serve disk images under QEMU, and the CPU
usage in doing so is never more than a couple of %. Performance may not
match that of a decent SCSI/SATA adater & direct attached drives, but
it beats the crap out of my internal IDE drive, for only 1-2% more CPU
utilization during sustained data transfer. 

Regards,
Dan.
-- 
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