Bug 993530 - Reading from a physical cdrom is very slow, dmesg can show bad sectors
Reading from a physical cdrom is very slow, dmesg can show bad sectors
Product: Fedora
Classification: Fedora
Component: qemu (Show other bugs)
All Linux
unspecified Severity high
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Assigned To: Fedora Virtualization Maintainers
Fedora Extras Quality Assurance
Depends On:
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Reported: 2013-08-06 02:47 EDT by Nix\
Modified: 2013-12-16 14:43 EST (History)
13 users (show)

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Fixed In Version:
Doc Type: Bug Fix
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Clone Of:
Last Closed: 2013-12-16 14:43:59 EST
Type: Bug
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RHEL 7.3 requirements from Atomic Host:
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Description Nix\ 2013-08-06 02:47:05 EDT
Description of problem:

When i use a Windows CDROM for install it in a KVM machine, the reading of the cdrom is very slow, like 8x. The installation time is more prolonged and i can listen like the dvd-rom read slowly compared to virtualbox that make runs faster the cdrom like a native cdrom of the guest.

Version-Release number of selected component (if applicable):

Fedora 18 x86_64 up to date.
[    1.836184] systemd-udevd[119]: starting version 201
[    4.830171] systemd-udevd[231]: starting version 201
[    1.748126] scsi 3:0:0:0: CD-ROM            HL-DT-ST DVDRAM GH22NS50  TN03 PQ: 0 ANSI: 5
[    1.752890] sr0: scsi3-mmc drive: 48x/48x writer dvd-ram cd/rw xa/form2 cdda tray
[    1.753092] cdrom: Uniform CD-ROM driver Revision: 3.20
[    1.753281] sr 3:0:0:0: Attached scsi CD-ROM sr0

How reproducible:
always using a cdrom with qemu-kvm

Steps to Reproduce:
1.insert a windows xp sp2 cd
2.create a new virtual machine, kvm, ide, default all and select cdrom as source
3.install and listen and see the time compared with virtualbox and listen the sound of rotation of the cdrom motor, is very slow with qemu-kvm compared with virtualbox that sounds like native box (fedora 18 runs normal and faster).

Actual results:

Installations using cdrom are much more slower than using .iso image

Expected results:
cdrom reading using qemu-kvm equal faster than host (fedora 18)

Additional info:
Comment 1 Cole Robinson 2013-12-16 14:43:59 EST
The host cdrom passthrough in qemu is known to not be particularly reliable, so this isn't surprising.

F18 is end-of-life soon, so nothing is unlikely to change there. Please reopen if this bug still affects F20+

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