[Bug 574588] [NEW] The --nocache flag for qemu-nbd doesn't work

[Randy Barlow]

Public bug reported:

Binary package hint: qemu-kvm

If I try to attach a disk image using qemu-kvm to a network block
device, it will not work if I use the --nocache flag. Here is an
example:

$ qemu-nbd -c /dev/nbd7 --nocache whowho.qcow2
$ ls /dev/nbd7*
/dev/nbd7

If you look in dmesg, there aren't any mentions of the above commands.
However, this works:

$ sudo qemu-nbd -c /dev/nbd7 whowho.qcow2

$ ls /dev/nbd7*
/dev/nbd7  /dev/nbd7p1  /dev/nbd7p2

And in dmesg, I see this:

[ 8489.904028]  nbd7: p1 p2

The latter command doesn't actually always work. Sometimes it just takes
several tries. When it doesn't work, there are no error messages or any
mention in the logs about it not working. It would be nice if it would
give some more info about what is happening.

ProblemType: Bug
DistroRelease: Ubuntu 10.04
Package: qemu-kvm 0.12.3+noroms-0ubuntu9
ProcVersionSignature: Ubuntu 2.6.32-21.32-generic 2.6.32.11+drm33.2
Uname: Linux 2.6.32-21-generic x86_64
NonfreeKernelModules: wl
Architecture: amd64
Date: Mon May  3 12:12:57 2010
EcryptfsInUse: Yes
InstallationMedia: Ubuntu 9.10 "Karmic Koala" - Release amd64 (20091027)
KvmCmdLine: Error: command ['ps', '-C', 'kvm', '-F'] failed with exit code 1: UID        PID  PPID  C    SZ   RSS PSR STIME TTY          TIME CMD
MachineType: Dell Inc. Latitude E6500
PccardctlIdent:
 Socket 0:
   no product info available
PccardctlStatus:
 Socket 0:
   no card
ProcCmdLine: BOOT_IMAGE=/boot/vmlinuz-2.6.32-21-generic root=UUID=3c7abe9e-d3a4-4123-b57f-2a41b13a3fcd ro quiet splash
ProcEnviron:
 LANG=en_US.utf8
 SHELL=/bin/bash
SourcePackage: qemu-kvm
dmi.bios.date: 09/17/2009
dmi.bios.vendor: Dell Inc.
dmi.bios.version: A16
dmi.board.name: 0W612R
dmi.board.vendor: Dell Inc.
dmi.chassis.type: 8
dmi.chassis.vendor: Dell Inc.
dmi.modalias: dmi:bvnDellInc.:bvrA16:bd09/17/2009:svnDellInc.:pnLatitudeE6500:pvr:rvnDellInc.:rn0W612R:rvr:cvnDellInc.:ct8:cvr:
dmi.product.name: Latitude E6500
dmi.sys.vendor: Dell Inc.

** Affects: qemu-kvm (Ubuntu)
     Importance: Undecided
         Status: New


** Tags: amd64 apport-bug lucid

-- 
The --nocache flag for qemu-nbd doesn't work
https://bugs.launchpad.net/bugs/574588
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