Comment 0 for bug 1336541

Néher Márton (neher-marton) wrote :

Hi,

As USB attached SSDs are becoming quite big and affordable, along comes the idea of installing systems on these.
But with current USB drivers, some functionality seems to be missing from USB subsystem.

The system does not recognize it is an SSD, but it is corrected manually:
# cat /etc/udev/rules.d/10-forcessd.rules
SUBSYSTEM=="block", ATTRS{vendor}=="SanDisk", ATTRS{model}=="Extreme", KERNEL=="sd?", ATTR{queue/rotational}="0"

# cat /sys/block/sdb/queue/rotational
0

Checked hdparm, it is saying I have TRIM on the device:
root@dome-stick:~# hdparm -I /dev/sdb

/dev/sdb:

ATA device, with non-removable media
 Model Number: SanDisk pSSD
(...)
Commands/features:
 Enabled Supported:
(...)
    * Data Set Management TRIM supported (limit 8 blocks)
    * Deterministic read ZEROs after TRIM
(...)

Here is appropriate dmesg:
[ 3.815604] usb 2-8: Manufacturer: SunplusIT INC.
[ 4.122002] usb 3-3: new SuperSpeed USB device number 2 using xhci_hcd
[ 4.138402] usb 3-3: New USB device found, idVendor=0781, idProduct=5580
[ 4.138404] usb 3-3: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[ 4.138405] usb 3-3: Product: Extreme
[ 4.138406] usb 3-3: Manufacturer: SanDisk
[ 4.138407] usb 3-3: SerialNumber: AA011109131654094942
[ 4.141393] usb-storage 3-3:1.0: USB Mass Storage device detected
[ 4.141431] scsi0 : usb-storage 3-3:1.0
[ 4.141703] usbcore: registered new interface driver usb-storage

And:
[ 5.331311] sd 0:0:0:0: [sdb] 122544516 512-byte logical blocks: (62.7 GB/58.4 GiB)
[ 5.331608] sd 0:0:0:0: [sdb] Write Protect is off
[ 5.331611] sd 0:0:0:0: [sdb] Mode Sense: 33 00 00 08
[ 5.331855] sd 0:0:0:0: [sdb] Write cache: disabled, read cache: enabled, doesn't support DPO or FUA
[ 5.339849] sdb: sdb1 sdb2 sdb3 < sdb5 >
[ 5.340783] sd 0:0:0:0: [sdb] Attached SCSI disk

From here I'll be using /boot formatted to ext4 to eliminate luks,lvm and btrfs from the equasion:

# mount |grep sdb2
/dev/sdb2 on /boot type ext4 (rw,noexec,discard)

# fstrim -v /boot/
fstrim: /boot/: FITRIM ioctl failed: Operation not supported

# strace fstrim -v /boot/
(...)
open("/boot/", O_RDONLY) = 3
ioctl(3, FITRIM, 0x7fffdded85c0) = -1 EOPNOTSUPP (Operation not supported)
(...)

During debugging, I've tried compiling a kernel with UAS module to check, it booted, worked fine, but it seems it wasn't used at all.
Any ideas why TRIM is not working on USB?
Any timeframes for possible fix?
Any workarounds maybe?