Dear Linux folks,
Probably, I am overlooking something, but testing a RAID6 setup with
loop-mounted fails on 16 GB RAM system (AMD and Intel), results in the
errors below. This happens with Linux 4.19.57 and 5.10.24 for example.
$ cd /dev/shm
$ for i in $(seq 1 16); do truncate -s 512M vdisk$i.img; done
[…]
$ sudo mdadm --create /dev/md1 --level=6 --raid-devices=16
/dev/loop{0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15}
$ dmesg
[…]
[879198.509123] md/raid:md1: not clean -- starting background reconstruction
[879198.515895] md/raid:md1: device loop15 operational as raid disk 15
[879198.522115] md/raid:md1: device loop14 operational as raid disk 14
[879198.528323] md/raid:md1: device loop13 operational as raid disk 13
[879198.534525] md/raid:md1: device loop12 operational as raid disk 12
[879198.540724] md/raid:md1: device loop11 operational as raid disk 11
[879198.546924] md/raid:md1: device loop10 operational as raid disk 10
[879198.553126] md/raid:md1: device loop9 operational as raid disk 9
[879198.559155] md/raid:md1: device loop8 operational as raid disk 8
[879198.565185] md/raid:md1: device loop7 operational as raid disk 7
[879198.571212] md/raid:md1: device loop6 operational as raid disk 6
[879198.577238] md/raid:md1: device loop5 operational as raid disk 5
[879198.583269] md/raid:md1: device loop4 operational as raid disk 4
[879198.589296] md/raid:md1: device loop3 operational as raid disk 3
[879198.595324] md/raid:md1: device loop2 operational as raid disk 2
[879198.601353] md/raid:md1: device loop1 operational as raid disk 1
[879198.607381] md/raid:md1: device loop0 operational as raid disk 0
[879198.613971] md/raid:md1: raid level 6 active with 16 out of 16
devices, algorithm 2
[879198.621667] md1: detected capacity change from 0 to 7486832640
[879198.627643] md: resync of RAID array md1
[879203.512870] blk_update_request: I/O error, dev loop5, sector 1001648
op 0x0:(READ) flags 0x0 phys_seg 1 prio class 0
[879203.512872] blk_update_request: I/O error, dev loop6, sector 1001648
op 0x0:(READ) flags 0x0 phys_seg 1 prio class 0
[879203.512874] blk_update_request: I/O error, dev loop7, sector 1001648
op 0x0:(READ) flags 0x0 phys_seg 1 prio class 0
[879203.512878] blk_update_request: I/O error, dev loop8, sector 1001656
op 0x0:(READ) flags 0x0 phys_seg 1 prio class 0
[879203.512880] blk_update_request: I/O error, dev loop9, sector 1001656
op 0x0:(READ) flags 0x0 phys_seg 1 prio class 0
[879203.512882] blk_update_request: I/O error, dev loop10, sector
1001656 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 0
[879203.512884] blk_update_request: I/O error, dev loop11, sector
1001656 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 0
[879203.512885] blk_update_request: I/O error, dev loop12, sector
1001656 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 0
[879203.512886] blk_update_request: I/O error, dev loop13, sector
1001656 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 0
[879203.512887] blk_update_request: I/O error, dev loop15, sector
1001656 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 0
[879203.526116] md/raid:md1: 558 read_errors > 557 stripes
[879203.526117] md/raid:md1: 558 read_errors > 557 stripes
[879203.526118] md/raid:md1: 558 read_errors > 557 stripes
[879203.526118] md/raid:md1: Too many read errors, failing device loop6.
[879203.526118] md/raid:md1: Too many read errors, failing device loop7.
[879203.526119] md/raid:md1: Disk failure on loop6, disabling device.
md/raid:md1: Operation continuing on 15 devices.
[879203.526120] md/raid:md1: Disk failure on loop7, disabling device.
md/raid:md1: Operation continuing on 14 devices.
[879203.526127] md/raid:md1: read error not correctable (sector 1002288
on loop9).
[879203.526128] md/raid:md1: read error not correctable (sector 1002288
on loop10).
[879203.526129] md/raid:md1: read error not correctable (sector 1002288
on loop8).
[879203.526130] md/raid:md1: read error not correctable (sector 1002288
on loop11).
[879203.526131] md/raid:md1: read error not correctable (sector 1002288
on loop12).
[879203.526134] md/raid:md1: read error not correctable (sector 1002288
on loop15).
[879203.526136] md/raid:md1: read error not correctable (sector 1002280
on loop2).
[879203.526137] md/raid:md1: read error not correctable (sector 1002280
on loop0).
[879203.526138] md/raid:md1: read error not correctable (sector 1002288
on loop2).
[879203.526139] md/raid:md1: read error not correctable (sector 1002288
on loop4).
[879203.528980] md: md1: resync interrupted.
[879203.746692] md/raid:md1: Too many read errors, failing device loop5.
[879203.765274] md: resync of RAID array md1
[879203.769254] md: md1: resync done.
[879220.534393] md1: detected capacity change from 7486832640 to 0
[879220.540270] md: md1 stopped.
$ sudo mdadm -S /dev/md1 && sudo losetup -D && rm vdisk*
```
Kind regards,
Paul
