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My system hangs from time to time when reading imperfect CD-R/DVD-R (slow reading speed from the drive). It is like the filesystem's IO lags and every time an application wants to read or write something, it "hangs" for seconds. The problem does not exist when the support is perfect (fast rotation speed of the drive).

Is there some tuning that can be done to prevent this annoying behaviour or is this purely hardware related? I don't remember having such issues with older IDE material... It is a plextor sata CD/DVD writer. Here some system information.

nicolas@nicolas-ad21:~$ dmesg | grep sd
[    1.717049] sd 0:0:0:0: Attached scsi g
eneric sg0 type 0
[    1.717077] sd 0:0:0:0: [sda] 1953525168 512-byte logical blocks: (1.00 TB/931 GiB)
[    1.717886] sd 0:0:0:0: [sda] Write Protect is off
[    1.717888] sd 0:0:0:0: [sda] Mode Sense: 00 3a 00 00
[    1.719880] sd 0:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
[    1.742304]  sda: sda1 sda2 sda3
[    1.743164] sd 0:0:0:0: [sda] Attached SCSI disk
[    2.397358] sd 1:0:1:0: Attached scsi generic sg2 type 0
[    2.397399] sd 1:0:1:0: [sdb] 390719855 512-byte logical blocks: (200 GB/186 GiB)
[    2.397641] sd 1:0:1:0: [sdb] Write Protect is off
[    2.397644] sd 1:0:1:0: [sdb] Mode Sense: 00 3a 00 00
[    2.397764] sd 1:0:1:0: [sdb] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
[    2.409299]  sdb: sdb1
[    2.409729] sd 1:0:1:0: [sdb] Attached SCSI disk
[    2.819527] EXT4-fs (sda1): mounted filesystem with ordered data mode. Opts: (null)
[   13.019456] Adding 16779888k swap on /dev/sda2.  Priority:-1 extents:1 across:16779888k FS
[   15.941584] EXT4-fs (sda1): re-mounted. Opts: errors=remount-ro
[   16.171196] EXT4-fs (sda3): mounted filesystem with ordered data mode. Opts: (null)
[   17.110190] Installing knfsd (copyright (C) 1996 [email protected]).
[   47.756673] type=1400 audit(1420184351.112:75): apparmor="STATUS" operation="profile_replace" profile="unconfined" name="/usr/sbin/cupsd" pid=2232 comm="apparmor_parser"
[   47.756912] type=1400 audit(1420184351.112:76): apparmor="STATUS" operation="profile_replace" profile="unconfined" name="/usr/sbin/cupsd" pid=2232 comm="apparmor_parser"
[ 1175.944841] type=1400 audit(1420185477.652:78): apparmor="STATUS" operation="profile_replace" profile="unconfined" name="/usr/sbin/cupsd" pid=2654 comm="apparmor_parser"
[ 1175.945116] type=1400 audit(1420185477.652:79): apparmor="STATUS" operation="profile_replace" profile="unconfined" name="/usr/sbin/cupsd" pid=2654 comm="apparmor_parser"
[15713.652746] sd 4:0:0:0: Attached scsi generic sg3 type 0
[15713.653242] sd 4:0:0:0: [sdc] 1250263728 512-byte logical blocks: (640 GB/596 GiB)
[15713.654530] sd 4:0:0:0: [sdc] Write Protect is off
[15713.654533] sd 4:0:0:0: [sdc] Mode Sense: 21 00 00 00
[15713.655632] sd 4:0:0:0: [sdc] No Caching mode page found
[15713.655635] sd 4:0:0:0: [sdc] Assuming drive cache: write through
[15713.658389] sd 4:0:0:0: [sdc] No Caching mode page found
[15713.658392] sd 4:0:0:0: [sdc] Assuming drive cache: write through
[15713.681978]  sdc: sdc1
[15713.715017] sd 4:0:0:0: [sdc] No Caching mode page found
[15713.715023] sd 4:0:0:0: [sdc] Assuming drive cache: write through
[15713.715027] sd 4:0:0:0: [sdc] Attached SCSI disk

Thanks for any clue on this.

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What you're experiencing is indeed nearly broken CD/DVDs still being read (even though with enormous difficulties).

The solution is simple: Copy the CD/DVD to a new disk and the problem will be gone!

Do this soon as humanly possible and start with the worst of them as continuing to do what you're doing, will eventually result in more scratches on the disk's transparent layer (in your case probably semi-transparent layer) and eventually the disk will stop being read for ever.

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  • Also: store CD-R and DVD-R's away from sunlight (in a closed file in a dark cupboard) as they do degrade due to UV light!
    – Fabby
    Jan 3, 2015 at 16:45

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