Using swapcache to speed up external disk writes?

Matthew Dillon dillon at
Fri Jan 9 19:10:49 PST 2015

Anything with the Silicon Image 3132 in it will work quite well.  Search
for that and you should find a bunch of PCIe x 1 cards that use the chip.
Provides two SATA ports (internal or external, depending on the card).


On Fri, Jan 9, 2015 at 1:43 PM, ejc <eric.j.christeson at> wrote:

> On Wed, Dec 17, 2014 at 11:41 AM, Matthew Dillon <dillon at>
> wrote:
>> 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.
> Thanks,
> Eric
> --
> "Suburbia is where the developer bulldozes out the trees,
>  then names the streets after them." -- Bill Vaughn
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