On Thu, Feb 15, 2024 at 12:09:20PM +0100, Martin Steigerwald wrote: > Kent Overstreet - 12.02.24, 21:42:26 CET: > > [thoughts about whether a cache flush / FUA request with write caches > disabled would be a no-op anyway] > > > > I may test the Transcend XS2000 with BTRFS to see whether it makes a > > > difference, however I really like to use it with BCacheFS and I do not > > > really like to use LUKS for external devices. According to the kernel > > > log I still don't really think those errors at the block layer were > > > about anything filesystem specific, but what do I know? > > > > It's definitely not unheard of for one specific filesystem to be > > tickling driver/device bugs and not others. > > > > I wonder what it would take to dump the outstanding requests on device > > timeout. > > I got some reply back from Transcend support. > > They brought up two possible issues: > > 1) Copied to many files at once. I am not going to accept that one. An > external 4 TB SSD should handle writing 1,4 TB in about 215000 files, > coming from a slower Toshiba Canvio Basics external HD, just fine. About > 90000 files was larger files like sound and video files or installation > archives. The rest is from a Linux system backup, so smaller files. I > likely move those elsewhere before I try again as I do not need these on > flash anyway. However if the amount of files or data matters I could never > know what amount of data I could write safely in one go. That is not > acceptable to me. > > 2) Power management related to USB port. Cause I am using a laptop. It may > have been that the Linux kernel decided to put the USB port the SSD was > connected to into some kind of sleep state. However it was a constant > rsync based copy workload. Yes, the kernel buffers data and the reads from > Toshiba HD should be quite a bit slower than the Transcend SSD could > handle the writes. I saw now more than 80-90 MiB/s coming from the hard > disk. However I would doubt this lead to pauses of write activity of more > than 30 seconds. Still it could be a thing. > > Regarding further testing I am unsure whether to first test with BTRFS on > top of LUKS – I do not like to store clear text data on the SSD – or with > BCacheFS plus fixes which are 6.7.5 or 6.8-rc4 in just in the case the flush > handling fixes would still have an influence on the issue at hand. > > First I will have a look on how to see what USB power management options > may be in place and how to tell Linux to keep the USB port the SSD is > connected to at all times. > > Let's see how this story unfolds. At least I am in no hurry about it. This may not be an issue of power management but rather one of insufficient power. A laptop may not provide enough power through its USB ports for the Transcend SSD to work properly under load. You can test this by connecting a powered UBS-3 hub between the laptop and the drive. Alan Stern
