kernel 6.5.x and usb write speeds gone to pot?

mikeymike · Post by **mikeymike** » Sun Feb 11, 2024 6:34 am

Yesterday evening and this morning I've been doing backups to a bunch of SATA hard drives and I've been noticing transfer rates being very far off what I would normally expect, ie. if large files (let's say >1GB) files are being transferred from a perfectly capable internal SATA drive (Seagate IronWolf NAS ST4000VN008, CMR, 7200RPM, 4TB) to the same model of drive via a USB enclosure, I'll see peak figures that are within expectations (about 180MB/sec), then inexplicably mid-transfer the rate drops to <1MB/sec. Where I would normally expect a backup to take maybe 15-25 minutes, I'm sometimes getting rsync ETAs in the region of 22 hours. I'm using iotop to confirm the slow transfer speeds.

The other drives I've transferred to are older drives, for example a 3.5" WD Black 1TB, 3.5" WD Blue 1TB. I know that all the drives I'm using are capable of at least (sustained) 100MB/sec write. The only other things I can think of trying are another enclosure and another USB3-HDD cable, but I'm doubtful of either being the cause since no errors/warnings are being reported in dmesg. I saw that another kernel update was due in Update Manager so I let that run and then rebooted but it hasn't helped. I'm pretty sure kernel 6.2.x didn't have this problem.

Is anyone else seeing similar issues?

- edit -

I've tried two enclosures (one has a molded USB3 cable so different cables too), set up a test and here's the results, both enclosures to my fastest drive showing extremely variable transfer rates:

Code: Select all

Fireflyus D1-1.mkv
  2,848,063,982 100%  115.59MB/s    0:00:23 (xfr#1, to-chk=12/14)
Fireflyus D1-2.mkv
  2,741,082,640 100%  124.36MB/s    0:00:21 (xfr#2, to-chk=11/14)
Fireflyus D1-3.mkv
  2,162,073,806 100%   60.58MB/s    0:00:34 (xfr#3, to-chk=10/14)
Fireflyus D1-4.mkv
  2,504,786,904 100%  104.29MB/s    0:00:22 (xfr#4, to-chk=9/14)
Fireflyus D2-1.mkv
  1,581,060,642 100%  128.51MB/s    0:00:11 (xfr#5, to-chk=8/14)
Fireflyus D2-2.mkv
  1,261,870,188 100%   59.37MB/s    0:00:20 (xfr#6, to-chk=7/14)
Fireflyus D2-3.mkv
  2,574,461,540 100%   92.04MB/s    0:00:26 (xfr#7, to-chk=6/14)
Fireflyus D2-4.mkv
  1,899,671,214 100%  145.84MB/s    0:00:12 (xfr#8, to-chk=5/14)
Fireflyus D3-1.mkv
  1,015,297,628 100%  151.17MB/s    0:00:06 (xfr#9, to-chk=4/14)
Fireflyus D3-2.mkv
  1,659,358,596 100%   57.74MB/s    0:00:27 (xfr#10, to-chk=3/14)
Fireflyus D3-3.mkv
  1,077,734,581 100%  155.96MB/s    0:00:06 (xfr#11, to-chk=2/14)
Fireflyus D3-4.mkv
  1,862,200,110 100%  149.94MB/s    0:00:11 (xfr#12, to-chk=1/14)
Fireflyus D3-5.mkv
  1,749,886,028 100%   60.38MB/s    0:00:27 (xfr#13, to-chk=0/14)

sent 24,943,637,018 bytes  received 266 bytes  101,191,226.30 bytes/sec
total size is 24,937,547,859  speedup is 1.00
mike@mikepc:~$ rm -rf /media/veracrypt1/Firefly/
mike@mikepc:~$ mkdir /media/veracrypt1/Firefly
mike@mikepc:~$ rsync -a -v -stats --progress /sourcedrive/Firefly/ /media/veracrypt1/Firefly/
sending incremental file list
./
Fireflyus D1-1.mkv
  2,848,063,982 100%  107.94MB/s    0:00:25 (xfr#1, to-chk=12/14)
Fireflyus D1-2.mkv
  2,741,082,640 100%  120.07MB/s    0:00:21 (xfr#2, to-chk=11/14)
Fireflyus D1-3.mkv
  2,162,073,806 100%   70.85MB/s    0:00:29 (xfr#3, to-chk=10/14)
Fireflyus D1-4.mkv
  2,504,786,904 100%  127.57MB/s    0:00:18 (xfr#4, to-chk=9/14)
Fireflyus D2-1.mkv
  1,581,060,642 100%   51.52MB/s    0:00:29 (xfr#5, to-chk=8/14)
Fireflyus D2-2.mkv
  1,261,870,188 100%  159.31MB/s    0:00:07 (xfr#6, to-chk=7/14)
Fireflyus D2-3.mkv
  2,574,461,540 100%  159.56MB/s    0:00:15 (xfr#7, to-chk=6/14)
Fireflyus D2-4.mkv
  1,899,671,214 100%   62.65MB/s    0:00:28 (xfr#8, to-chk=5/14)
Fireflyus D3-1.mkv
  1,015,297,628 100%  160.41MB/s    0:00:06 (xfr#9, to-chk=4/14)
Fireflyus D3-2.mkv
  1,659,358,596 100%   58.51MB/s    0:00:27 (xfr#10, to-chk=3/14)
Fireflyus D3-3.mkv
  1,077,734,581 100%  160.47MB/s    0:00:06 (xfr#11, to-chk=2/14)
Fireflyus D3-4.mkv
  1,862,200,110 100%  154.99MB/s    0:00:11 (xfr#12, to-chk=1/14)
Fireflyus D3-5.mkv
  1,749,886,028 100%  160.53MB/s    0:00:10 (xfr#13, to-chk=0/14)

sent 24,943,637,018 bytes  received 266 bytes  107,284,461.44 bytes/sec
total size is 24,937,547,859  speedup is 1.00

It's not an issue with the encryption either as one of my backups is to an unencrypted drive and I saw similarly variable throughput. A transfer might kick off for a bit at ~190MB/sec then halfway through it drops to zero for several seconds (according to iotop). The drive access light on the enclosure denotes activity during this "idle" period, system activity including the source disk seems virtually idle.