Tiered/cached storage and DragonFlyBSD

[Michael Neumann]

On Tue, Aug 21, 2018 at 10:40:14PM +0800, Aaron LI wrote:
> On Tue, 21 Aug 2018 16:12:37 +0200
> "my123 (@never_released)" <securetalk at sbmobilepilot.onmicrosoft.com> wrote:
> 
> > On my laptop, I use a DragonFlyBSD VM with NFS to use HAMMER2 features. 
> > (ZFS for example doesn't support on-demand deduplication).
> > 
> > Is there any way to combine a part of my SSD with the comparatively huge 
> > HDD to make burst writes better (and have them committed to HDD later, 
> > in times of low loads)? Linux supports this usecase better, but it 
> > doesn't have a good filesystem for my usecase.
> > 
> 
> Hi,
> 
> Thanks for using DragonFly.
> 
> I believe our swapcache(8) is what you need.  Please read the nice
> swapcache(8) man page (http://mdoc.su/d/swapcache ), and you can find
> detailed description and examples.

Except that swapcache(8) doesn't handle writes ;-). If you are looking
for something equivalent to ZFS's ZIL which you can put on a SSD, there
isn't one. Still, swapcache(8) is a great way to improve your harddisk
reads.

Regards,

  Michael