Using swapcache to speed up external disk writes?

ejc eric.j.christeson at
Fri Jan 9 13:43:07 PST 2015

On Wed, Dec 17, 2014 at 11:41 AM, Matthew Dillon <dillon at>

> Swapcache will speed up accesses to the external disk very nicely, but not
> have much of an effect on write performance.  But writes are already
> buffered to some degree, and NFS clients usually flush modifies files on
> close() for safety reasons (which might be why you see some latency).  That
> can often be turned off on the client but I do not recommend doing so.
> The main problem with USB-attached drives is that the I/Os are basically
> serialized, so random access performance is going to be horrible.  For a
> server you really need a SATA attached drive.  Swapcache will improve
> random access performance though once things get cached.
Speaking of which, does anyone have a recommendation for an eSATA card or
chipset to look for that works well with DragonFly?  I've been using USB
drives for backups, but want to switch to something a little faster and
more reliable.  My computers don't have any extra internal SATA ports free
so I need an expansion card.


"Suburbia is where the developer bulldozes out the trees,
 then names the streets after them." -- Bill Vaughn
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