My M.2 SSD and adapter have arrived, and I've been investigating with
the tools described in the 'blog post that Paul linked to'
(https://lemariva.com/blog/2020/08/raspberry-pi-4-ssd-booting-enabled-trim).
I first of all investigated my existing Sandisk SATA SSD drive that's
connected via a cheapo SATA-to-USB adapter. The indications are that
it's unmap-capable (but not enabled), and that it's using 'Bulk-Only
Transport' (BOT) and not UASP. No great surprises there, and I guess I
could implement unmap as per the instructions in the blog post.
Code:
--------------------
tc@pCPServer:/mnt/sdb2/tce$ fstrim -v /mnt/Music
fstrim: FITRIM: Operation not permitted
tc@pCPServer:/mnt/sdb2/tce$ sg_vpd -p bl /dev/sda
.
.
.
Maximum unmap LBA count: 4194240
Maximum unmap block descriptor count: 1
Optimal unmap granularity: 1 blocks
Unmap granularity alignment valid: false
Unmap granularity alignment: 0 [invalid]
.
.
.
tc@pCPServer:/mnt/sdb2/tce$ lsusb -v
Bus 002 Device 003: ID 174c:55aa ASMedia Technology Inc. ASM1051E SATA 6Gb/s
bridge, ASM1053E SATA 6Gb/s bridge, ASM1153 SATA 3Gb/s bridge, ASM1153E SATA
6Gb/s bridge
Device Descriptor:
.
.
.
Interface Descriptor:
.
.
bInterfaceClass 8 Mass Storage
bInterfaceSubClass 6 SCSI
bInterfaceProtocol 80 Bulk-Only
.
.
.
--------------------
I then used the same commands on the new 'M.2 SATA drive'
(https://www.amazon.co.uk/gp/product/B078WYS5K6) connected via the Argon
adapter. If I'm reading the output correctly, then this setup is NOT
unmap-capable, and is also using the BOT driver, rather than UASP.
That's a bit of a surprise, given the blurb on the 'Pi Hut page'
(https://thepihut.com/collections/raspberry-pi-cases/products/argon-one-m-2-raspberry-pi-4-case)
about UASP support. Perhaps I need to do something to enable it, or
perhaps I'm misreading the output.
Code:
--------------------
tc@pCP:~$ fstrim -v /mnt/m2
fstrim: FITRIM: Operation not permitted
tc@pCP:~$ sg_vpd -p bl /dev/sda
.
.
.
Maximum unmap LBA count: 0 [Unmap command not implemented]
Maximum unmap block descriptor count: 0 [Unmap command not implemented]
Optimal unmap granularity: 0 blocks [not reported]
Unmap granularity alignment valid: false
Unmap granularity alignment: 0 [invalid]
.
.
.
tc@pCP:~$ lsusb -v
Bus 002 Device 002: ID 174c:55aa ASMedia Technology Inc. ASM1051E SATA 6Gb/s
bridge, ASM1053E SATA 6Gb/s bridge, ASM1153 SATA 3Gb/s bridge, ASM1153E SATA
6Gb/s bridge
Device Descriptor:
.
.
.
Interface Descriptor:
.
.
bInterfaceClass 8 Mass Storage
bInterfaceSubClass 6 SCSI
bInterfaceProtocol 80 Bulk-Only
.
.
.
--------------------
I also did a few rudimentary speed tests, as per the instructions on
'this page' (https://elinux.org/RPi_SD_cards#Terminal_Commands).
I found that my old SATA drive achieves a write speed of around 150MB/s
and read speed of around 210MB/s.
The new M.2 SATA drive achieves a write speed of around 245MB/s and a
read speed of around 300MB/s.
These are all somewhat short of the 5Gbps possible under USB3, but hey,
at least the new M.2 drive seems to be about 50% faster than the SSD
I've been using. And since it's only used to store a largely static
music collection, both drives are more than fast enough.
------------------------------------------------------------------------
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View this thread: http://forums.slimdevices.com/showthread.php?t=113575
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