Guest Disk Performance Slow

risq

New Member
Jul 2, 2011
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Hi,

i created a KVM Virtual Machine Ubuntu (11.04) and wonder why the Data Transfer performance is so slow.

Samba is used for Filetransfer between the Ubuntu guest and a network client. I only get 5-10MB/s.

For comparison i installed a Samba Server directly on the Proxmox Host ("v1"), there i get 80 MB/s to the same client, so there must be some problem with the guests. I know there is some performance loss when running guests, but that cant explain that slow transfer.

I used Image Format qcow2, Disk Type Virtio and Network Card Virtio No tweaking else, everything created from the Gui.

Some more information: Proxmox 1.8, Kernel Linux v1 2.6.35 (upgraded from 2.6.32, but didnt changed anything, Guest Transfer Performance was bad on both Kernels)

My Disk Performance on the Host with my 2 Harddrives:

v1:~# hdparm -tT /dev/sda

/dev/sda:
Timing cached reads: 2304 MB in 2.00 seconds = 1151.78 MB/sec
Timing buffered disk reads: 254 MB in 3.02 seconds = 84.21 MB/sec
v1:~# hdparm -tT /dev/sdb

/dev/sdb:
Timing cached reads: 2380 MB in 2.00 seconds = 1190.25 MB/sec
Timing buffered disk reads: 254 MB in 3.01 seconds = 84.48 MB/sec

Any hints?