Bug 197715

Summary:	No TRIM with Samstung T5 external SSD
Product:	IO/Storage	Reporter:	Sven Köhler (sven.koehler)
Component:	Other	Assignee:	io_other
Status:	NEW ---
Severity:	normal	CC:	sven.koehler, teuniz
Priority:	P1
Hardware:	All
OS:	Linux
Kernel Version:	5.4.10	Subsystem:
Regression:	No	Bisected commit-id:

Description Sven Köhler 2017-11-02 22:38:01 UTC

The Samsung T5 has a USB to SATA bridge with UAS. According to [1] it uses the ASMedia ASM235CM bridge chip.

I do not know whether the ASM235CM has proper support for TRIM (whatever that means) or it is only supported at the ATA pass-through level (which causes issue with command queuing I guess?).

Can TRIM be support with this sort of drive? Or will it remain unsupported?
fstrim fails for me with "the discard operation is not supported".


[1] https://www.anandtech.com/show/11719/samsung-portable-ssd-t5-review-64layer-vnand-debuts-in-retail

Comment 1 Sven Köhler 2017-11-08 23:44:04 UTC

It is claimed at [2] that the UASP to SATA bridge must convert SCSI UNMAP to TRIM commands. I do not know, whether the ASM235CM used in the Samsung T5 supports that. Would Linux support fstrim on an UASP drive if UNMAP was supported?

Windows 10 has no problem to "optimize" (MS-equivalent of fstrim) the NTFS partition on my SSD while I cannot fstrim the ext4 partition on the SSD.

[2] https://blog.startech.com/post/all-you-need-to-know-about-uasp/