[rescue] [FWIW] RaSCSI

[Joshua D. Boyd]

> On Feb 21, 2022, at 4:02 PM, Lionel Peterson <lionel4287 at gmail.com> wrote:
>
> Let's not forget the absolute performance ceiling imposed by using a
MicroSD
> card for the actual storage medium.
>
> It would be interesting to see performance comparisons between spinning SCA
> SCSI drives and any of these MicroSD card-based alternatives.
>
> An SCA sled that takes SATA SSD would be great, anyone know about any?

Not that any of the discussed SD -> SCSI adapters can do this, but a modern
uSD card in a good USB3.0 uSD reader can deliver very good performance.

The 2010 Seagate Cheetah 15K.5 drives claim to sustain 73-125MBps transfer
speed (under optimal conditions) and have a typical seek time of over 3ms,
which is about 330 iOPS.

For uSD cards that are rated A1/U1, you will get better iOPS (but not typical
sata SSD iOPS by any means) and a transfer rate that falls in the range of
that Cheetah. I havenbt specifically tested the iOPS, but I can attest to
transfer rates like that with my Kingston and Lexar USB3 uSD readers.  There
are faster still uSD card ratings, but I havenbt specifically tested them.

Typically I stick to SanDisk or Samsung uSD cards  (although I suppose that
Kingston and Lexar are likely just as good) bought from B&H in hopes that B&H
is less likely to have counterfeit uSD cards.

What I typically use the cards for isnbt typically that performance
sensitive, but I spend enough time writing images to the cards that I figured
it was worth spending a little more to speed that process up and it has made a
large quality of life improvement for me.