poor rsync performance with specific Linux kernel version?
Michael Doerner - TechnologyWise
michael at tw.co.nz
Tue May 17 16:31:03 MDT 2011
I am new to this list but a happy rsync user for quite some time. Thanks
for this great tool.
We are experiencing very slow rsync performance when using it as a
backup tool for our server virtualisation "Proxmox VE"
I have searched for our issue and posted at the Proxmox forums (
but no results so I hope to ask the question here properly:
Trying to rsync an 8 GB testfile (dd if=/dev/zero
of=/var/lib/vz/testfile_MDO bs=1024k count=8192 conv=fdatasync) on quite
a high-end system (Supermicro "X8DTI-F" board, 12 GB RAM, SAS disks on
Adaptec RAID controller) running Proxmox with a (Debian) Linux kernel at
rsync --progress /var/lib/vz/testfile_MDO /var/lib/vz/testfile_MDO2
592379904 6% 949.34kB/s 2:20:24 ^C
I had to cancel due to the low speed at that time.
The issue seems related to the specific combination of hardware and that
particular kernel (Proxmox' "Debian" kernel 2.6.32). If I replace that
kernel with their alternative "Redhat" 2.6.18 kernel version, the same
rsync process is fast and will sync/copy the 8GB file in less than 2
We can replicate the slow speed problem on two other servers which use
almost identical hardware. Can I get any help or idea here on this list
what I could try to further isolate this issue?
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