Yes I know. The disk always ran great (as it did recently on the Pi) and I was a little too stingy to buy one with an external PSU anyway.
However, I have already ordered a new disk (this time with external PSU ;D).
After running the command you posted, I get the following output:
root@DietPi:~# dmesg -l err,crit,alert,emerg
[ 7.804474] brcmfmac: brcmf_fw_alloc_request: using brcm/brcmfmac43430-sdio for chip BCM43430/1
[ 8.121537] brcmfmac: brcmf_fw_alloc_request: using brcm/brcmfmac43430-sdio for chip BCM43430/1
[ 8.130572] brcmfmac: brcmf_fw_alloc_request: using brcm/brcmfmac43430-sdio for chip BCM43430/1
[ 8.130725] brcmfmac: brcmf_c_process_clm_blob: no clm_blob available (err=-2), device may have limited channels available
[ 8.132043] brcmfmac: brcmf_c_preinit_dcmds: Firmware: BCM43430/1 wl0: Oct 22 2019 01:59:28 version 7.45.98.94 (r723000 CY) FWID 01-3b33decd
[ 9.092004] Under-voltage detected! (0x00050005)
[ 72.684132] raspberrypi-firmware soc:firmware: Request 0x00048003 returned status 0x80000001
[ 72.684160] bcm2708_fb soc:fb: Failed to allocate GPU framebuffer (-22)
[ 72.684178] bcm2708_fb_pan_display(0,0) returns=-22
[ 88.602214] raspberrypi-firmware soc:firmware: Request 0x00048003 returned status 0x80000001
[ 88.602240] bcm2708_fb soc:fb: Failed to allocate GPU framebuffer (-22)
[ 88.602258] bcm2708_fb_pan_display(0,0) returns=-22
[ 593.740699] Under-voltage detected! (0x00050005)
[ 601.804875] Under-voltage detected! (0x00050005)
[ 628.013456] Under-voltage detected! (0x00050005)
[ 734.706502] sd 0:0:0:0: [sda] No Caching mode page found
[ 734.706525] sd 0:0:0:0: [sda] Assuming drive cache: write through
[ 967.668837] INFO: task kworker/u8:3:2408 blocked for more than 120 seconds.
[ 967.668921] Not tainted 5.10.63-v8+ #1459
[ 967.668937] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 1016.470887] sd 0:0:0:0: [sda] tag#0 timing out command, waited 180s
[ 1016.471114] blk_update_request: I/O error, dev sda, sector 0 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 0
[ 1016.471155] Buffer I/O error on dev sda, logical block 0, async page read
[ 1069.195784] blk_update_request: I/O error, dev sda, sector 0 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 0
[ 1069.195812] Buffer I/O error on dev sda, logical block 0, async page read
[ 1069.210995] blk_update_request: I/O error, dev sda, sector 0 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 0
[ 1069.211034] Buffer I/O error on dev sda, logical block 0, async page read
[26915.205315] Under-voltage detected! (0x00050005)
[27022.218266] sd 0:0:0:0: [sda] No Caching mode page found
[27022.218290] sd 0:0:0:0: [sda] Assuming drive cache: write through
[27303.815858] sd 0:0:0:0: [sda] tag#0 timing out command, waited 180s
[27303.815996] blk_update_request: I/O error, dev sda, sector 0 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 0
[27303.816023] Buffer I/O error on dev sda, logical block 0, async page read
[27430.448463] INFO: task kworker/u8:3:2408 blocked for more than 120 seconds.
[27430.448493] Not tainted 5.10.63-v8+ #1459
[27430.448508] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[27430.449315] INFO: task blkid:5454 blocked for more than 120 seconds.
[27430.449332] Not tainted 5.10.63-v8+ #1459
[27430.449347] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[27484.318080] sd 0:0:0:0: [sda] tag#0 timing out command, waited 180s
[27484.318303] blk_update_request: I/O error, dev sda, sector 0 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 0
[27484.318342] Buffer I/O error on dev sda, logical block 0, async page read
[27551.283130] INFO: task blkid:5454 blocked for more than 241 seconds.
[27551.283154] Not tainted 5.10.63-v8+ #1459
[27551.283180] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[27664.420317] sd 0:0:0:0: [sda] tag#0 timing out command, waited 180s
[27664.420539] blk_update_request: I/O error, dev sda, sector 0 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 0
[27664.420591] Buffer I/O error on dev sda, logical block 0, async page read
[27844.572561] sd 0:0:0:0: [sda] tag#0 timing out command, waited 180s
[27844.572782] blk_update_request: I/O error, dev sda, sector 9767475072 op 0x0:(READ) flags 0x80700 phys_seg 1 prio class 0
[28025.974823] sd 0:0:0:0: [sda] tag#0 timing out command, waited 180s
[28025.975038] blk_update_request: I/O error, dev sda, sector 9767475072 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 0
[28025.975091] Buffer I/O error on dev sda, logical block 1220934384, async page read
[28274.591327] sd 0:0:0:0: [sda] Asking for cache data failed
[28274.591349] sd 0:0:0:0: [sda] Assuming drive cache: write through
[28382.740969] sd 0:0:0:0: [sda] No Caching mode page found
[28382.740993] sd 0:0:0:0: [sda] Assuming drive cache: write through
[28638.794589] INFO: task kworker/u8:3:2408 blocked for more than 120 seconds.
[28638.794672] Not tainted 5.10.63-v8+ #1459
[28638.794688] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[28663.898030] sd 0:0:0:0: [sda] tag#0 timing out command, waited 180s
[28663.898168] blk_update_request: I/O error, dev sda, sector 0 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 0
[28663.898195] Buffer I/O error on dev sda, logical block 0, async page read
[28759.629196] INFO: task blkid:6452 blocked for more than 120 seconds.
[28759.629221] Not tainted 5.10.63-v8+ #1459
[28759.629237] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[28844.050339] sd 0:0:0:0: [sda] tag#0 timing out command, waited 180s
[28844.050565] blk_update_request: I/O error, dev sda, sector 0 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 0
[28844.050604] Buffer I/O error on dev sda, logical block 0, async page read
[28880.463831] INFO: task blkid:6452 blocked for more than 241 seconds.
[28880.463856] Not tainted 5.10.63-v8+ #1459
[28880.463935] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[29001.298474] INFO: task kworker/u8:3:2408 blocked for more than 120 seconds.
[29001.298498] Not tainted 5.10.63-v8+ #1459
[29001.298513] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[29001.299391] INFO: task blkid:6452 blocked for more than 362 seconds.
[29001.299408] Not tainted 5.10.63-v8+ #1459
[29001.299422] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[29026.002594] sd 0:0:0:0: [sda] tag#0 timing out command, waited 180s
[29026.002831] blk_update_request: I/O error, dev sda, sector 0 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 0
[29026.002871] Buffer I/O error on dev sda, logical block 0, async page read
[29206.254973] sd 0:0:0:0: [sda] tag#0 timing out command, waited 180s
[29206.255186] blk_update_request: I/O error, dev sda, sector 9767475072 op 0x0:(READ) flags 0x80700 phys_seg 1 prio class 0
[29386.507224] sd 0:0:0:0: [sda] tag#0 timing out command, waited 180s
[29386.507459] blk_update_request: I/O error, dev sda, sector 9767475072 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 0
[29386.507499] Buffer I/O error on dev sda, logical block 1220934384, async page read
[29926.568051] sd 0:0:0:0: [sda] tag#0 timing out command, waited 180s
[29926.568205] blk_update_request: I/O error, dev sda, sector 0 op 0x1:(WRITE) flags 0x4800 phys_seg 30 prio class 0
[29926.568231] Buffer I/O error on dev sda, logical block 0, lost async page write
[29926.568289] Buffer I/O error on dev sda, logical block 1, lost async page write
[29926.568323] Buffer I/O error on dev sda, logical block 2, lost async page write
[29926.568355] Buffer I/O error on dev sda, logical block 3, lost async page write
[29926.568388] Buffer I/O error on dev sda, logical block 4, lost async page write
[29926.568420] Buffer I/O error on dev sda, logical block 5, lost async page write
[29926.568453] Buffer I/O error on dev sda, logical block 6, lost async page write
[29926.568485] Buffer I/O error on dev sda, logical block 7, lost async page write
[29926.568518] Buffer I/O error on dev sda, logical block 8, lost async page write
[29926.568550] Buffer I/O error on dev sda, logical block 9, lost async page write
[29967.975294] INFO: task kworker/u8:0:6578 blocked for more than 120 seconds.
[29967.975324] Not tainted 5.10.63-v8+ #1459
[29967.975339] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[30108.370409] sd 0:0:0:0: [sda] tag#0 timing out command, waited 180s
[30108.370553] blk_update_request: I/O error, dev sda, sector 240 op 0x1:(WRITE) flags 0x4800 phys_seg 30 prio class 0
[30108.370586] Buffer I/O error on dev sda, logical block 30, lost async page write
[30108.370645] Buffer I/O error on dev sda, logical block 31, lost async page write
[30108.370691] Buffer I/O error on dev sda, logical block 32, lost async page write
[30108.370724] Buffer I/O error on dev sda, logical block 33, lost async page write
[30108.370757] Buffer I/O error on dev sda, logical block 34, lost async page write
[30108.370790] Buffer I/O error on dev sda, logical block 35, lost async page write
[30108.370822] Buffer I/O error on dev sda, logical block 36, lost async page write
[30108.370855] Buffer I/O error on dev sda, logical block 37, lost async page write
[30108.370888] Buffer I/O error on dev sda, logical block 38, lost async page write
[30108.370920] Buffer I/O error on dev sda, logical block 39, lost async page write
[30290.018887] sd 0:0:0:0: [sda] tag#0 timing out command, waited 180s
[30290.019035] blk_update_request: I/O error, dev sda, sector 480 op 0x1:(WRITE) flags 0x800 phys_seg 1 prio class 0
[30290.019068] Buffer I/O error on dev sda, logical block 60, lost async page write
[30471.825105] sd 0:0:0:0: [sda] tag#0 timing out command, waited 180s
[30471.825242] blk_update_request: I/O error, dev sda, sector 488 op 0x1:(WRITE) flags 0x104000 phys_seg 30 prio class 0
[30471.825268] Buffer I/O error on dev sda, logical block 61, lost async page write
[30471.825327] Buffer I/O error on dev sda, logical block 62, lost async page write
[30471.825361] Buffer I/O error on dev sda, logical block 63, lost async page write
[30471.825394] Buffer I/O error on dev sda, logical block 64, lost async page write
[30471.825438] Buffer I/O error on dev sda, logical block 65, lost async page write
[30471.825471] Buffer I/O error on dev sda, logical block 66, lost async page write
[30471.825504] Buffer I/O error on dev sda, logical block 67, lost async page write
[30471.825536] Buffer I/O error on dev sda, logical block 68, lost async page write
[30471.825568] Buffer I/O error on dev sda, logical block 69, lost async page write
[30471.825601] Buffer I/O error on dev sda, logical block 70, lost async page write
[30652.673544] sd 0:0:0:0: [sda] tag#0 timing out command, waited 180s
[30652.673701] blk_update_request: I/O error, dev sda, sector 728 op 0x1:(WRITE) flags 0x100000 phys_seg 1 prio class 0
[30652.673734] Buffer I/O error on dev sda, logical block 91, lost async page write
[30833.629770] sd 0:0:0:0: [sda] tag#0 timing out command, waited 180s
[30833.630033] blk_update_request: I/O error, dev sda, sector 736 op 0x1:(WRITE) flags 0x4800 phys_seg 30 prio class 0
[30833.630071] Buffer I/O error on dev sda, logical block 92, lost async page write
[30833.630142] Buffer I/O error on dev sda, logical block 93, lost async page write
[30833.630202] Buffer I/O error on dev sda, logical block 94, lost async page write
[30833.630250] Buffer I/O error on dev sda, logical block 95, lost async page write
[30833.630296] Buffer I/O error on dev sda, logical block 96, lost async page write
[30833.630342] Buffer I/O error on dev sda, logical block 97, lost async page write
[30833.630389] Buffer I/O error on dev sda, logical block 98, lost async page write
[30833.630435] Buffer I/O error on dev sda, logical block 99, lost async page write
[30833.630481] Buffer I/O error on dev sda, logical block 100, lost async page write
[30833.630527] Buffer I/O error on dev sda, logical block 101, lost async page write
[31015.606154] sd 0:0:0:0: [sda] tag#0 timing out command, waited 180s
[31015.606374] blk_update_request: I/O error, dev sda, sector 976 op 0x1:(WRITE) flags 0x4800 phys_seg 30 prio class 0
[31015.606433] Buffer I/O error on dev sda, logical block 122, lost async page write
[31015.606503] Buffer I/O error on dev sda, logical block 123, lost async page write
[31015.606562] Buffer I/O error on dev sda, logical block 124, lost async page write
[31015.606610] Buffer I/O error on dev sda, logical block 125, lost async page write
[31015.606656] Buffer I/O error on dev sda, logical block 126, lost async page write
[31015.606703] Buffer I/O error on dev sda, logical block 127, lost async page write
[31015.606748] Buffer I/O error on dev sda, logical block 128, lost async page write
[31015.606795] Buffer I/O error on dev sda, logical block 129, lost async page write
[31015.606841] Buffer I/O error on dev sda, logical block 130, lost async page write
[31015.606887] Buffer I/O error on dev sda, logical block 131, lost async page write
[31197.384405] sd 0:0:0:0: [sda] tag#0 timing out command, waited 180s
[31197.384635] blk_update_request: I/O error, dev sda, sector 1216 op 0x1:(WRITE) flags 0x4800 phys_seg 30 prio class 0
[31197.384708] Buffer I/O error on dev sda, logical block 152, lost async page write
[31197.384784] Buffer I/O error on dev sda, logical block 153, lost async page write
[31197.384834] Buffer I/O error on dev sda, logical block 154, lost async page write
[31197.384883] Buffer I/O error on dev sda, logical block 155, lost async page write
[31197.384929] Buffer I/O error on dev sda, logical block 156, lost async page write
[31197.384976] Buffer I/O error on dev sda, logical block 157, lost async page write
[31197.385023] Buffer I/O error on dev sda, logical block 158, lost async page write
[31197.385070] Buffer I/O error on dev sda, logical block 159, lost async page write
[31197.385117] Buffer I/O error on dev sda, logical block 160, lost async page write
[31197.385164] Buffer I/O error on dev sda, logical block 161, lost async page write
[31379.032771] sd 0:0:0:0: [sda] tag#0 timing out command, waited 180s
[31379.033008] blk_update_request: I/O error, dev sda, sector 1456 op 0x1:(WRITE) flags 0x100000 phys_seg 1 prio class 0
[31379.033071] Buffer I/O error on dev sda, logical block 182, lost async page write
In the beginning it seems to have problems with undervoltage. However, I wonder where these problems should suddenly come from out of nowhere. Or can other problems be read from the log?