View Full Version : [all variants] VM-Builder: 'unpacking' takes a lot of time...
March 30th, 2011, 12:42 PM
(I know it's a double post [showthread.php?p=10614120],
but I don't know how to move a question accross Categories.)
Hi Hi Everybody,
after some testing with the vmbuilder AND a local mirror
with all the packages, the system still needs more than
12 minutes for a clean and minimum VM-image...
Is there a way to speed this proces up?
With the --debug option I found out that the 'unpacking'
task takes, by far, the most time of building a VM...
(some people think its the EXT4 on the host !??)
I'm testing on three Ubuntu Server (10.04) KVM/QEmu Hosts
on three new Dell PowerEdge R310 RackServers.
The 64bit host os's are installed on two 2Tb mirrored SataHDDs
Thx in Advanced for any ideas..!!
March 31st, 2011, 05:21 PM
I know it for SURE..!
When I change the /tmp of the host OS from EXT4 to EXT3,
my vmbuilder builds the same VM in less than 4 minutes!!!!!
(in stad of more than 12 minutes)
Now I only have an other problem :sad:
When I build to a RAW logica volume (lvm),
the GUEST OS gives the following error:
EXT4-fs error (device sda1): ext4_mb_generate_buddy:
EXT4-fs group 2: 3431 blocks in bitmap, 3597 in gd
This looks like an conversion error from EXT3 to EXT4
on the guest OS!??
By the way...
When I build to a QCOW2 file, everything is/looks fine!!!
April 1st, 2011, 01:02 PM
Some extra info about EXT3 and EXT4 partition:
https://wiki.ubuntu.com/LucidLynx/ReleaseNotes#Performance regressions with ext4 under certain workloads
April 2nd, 2011, 06:55 PM
Sorry don't have much info to help here .. but please keep us informed of your findings :)
April 4th, 2011, 08:39 AM
I will keep this topic informed...
You could also subscribe to the bug report I made friday:
For now, I build my VM's the following way:
1.) VMBuilder (with the EXT3 /tmp partition) to a QCow2 file
2.) Convert the QCow2 file to a RAW file
3.) Create a new LVM logical volume
4.) sudo dd if=disk0.raw bs=512k of=/dev/vg-1/VM01-Disk0 (don't forget the option bs=512k !!)
5.) Minor adjustment to the xml in /etc/libvirt/qemu/
<disk type='block' device='disk'>
<driver name='qemu' type='raw' cache='none'/>
<target dev='vda' bus='virtio'/>
6.) :-) Done!
Today I'll try to script this...
Only #5 will be (for me) a difficult one.
By the way!
Some people have the following problem with VMBuilder:
"First everything seems to work ok, but soon after certain volume of traffic goes through the thing will freeze for a while. For example, I start copying 500 mb file. I will get 200 MB done superfast (50MB/s). Then everything will freeze for a while. After that copying resumes a bit slower for a few seconds and again, everything freezes."
This is because the QCow2 files. When you use RAW files or (just like me) a LVM logical volume. This problem is solved...
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