I believe Radian RMS-200/RMS-300 devices are still on sale (RAM disk with
PLP and flash), about $100 for 8Gb RMS-200 versions on eBay (2x-3x that for
newer RMS-300 which may be too good for a small home server, but also
younger component-wise).

I've got one card, but actually had trouble making use of in the main
system I wanted it for so far - that MoBo happens to be maxed out for PCI
lanes, and connecting a card disabled some SATA ports with actual HDDs. My
pool was very confused on subsequent boots. Too bad half the lanes are
wasted on a lowly video card just because there gotta be one for
troubleshooting.

Internet lore says these were popular with TrueNAS; but sale-offs may be
due to aging capacitors, so YMMV. The small cooler also screamed at an
uncomfortably high pitch, so I had mine neutered with tape ;)

Jim


On Wed, May 13, 2026, 02:17 Bill Sommerfeld via illumos-discuss <
[email protected]> wrote:

> On 5/12/26 15:12, Dan McDonald wrote:
> > On May 12, 2026, at 4:44 PM, Lionel Cons <[email protected]>
> > wrote:
> >>
> >> On Tue, 12 May 2026 at 19:43, Dan McDonald <[email protected]>
> >> wrote:
> >>>
> >>> On May 12, 2026, at 5:48 AM, Lionel Cons
> >>> <[email protected]> wrote:
> >>>>
> >>>> Are there suggestions on how to DRASTICALLY reduce Illumos
> >>>> nfsd I/O latency on ZFS?
> >>>
> >>> You're using a slog device on your pool, right?
> >>
> >> No, but I can try. Can slog devices be used for the root pool?
> >> Also, can slog devices be added and removes dynamically?
> >
> > Yes, and yes, respectively.  HIGHLY recommend the lowest-latency
> > device you can get your hands on for a slog.  Think "small but fast
> > NVMe drive.
> 
> For a slog device, one critical parameter is how fast a SYNCHRONIZE
> CACHE operation completes.  You want a device with a fast write cache
> with power-loss protection (PLP); they have enough onboard power storage
> in capacitors or supercaps that they can save the contents of the write
> buffer when the power goes out..
> 
> Among the devices I have in hand, a couple old SATA ssds with PLP
> outperform a couple M.2 NVMes lacking PLP by a factor of about 4.
> 
> If anyone's found decent small NVMe drives with PLP I want to hear
> about it...

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