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Akarot's questions

Martin Hope
Akarot
Asked: 2012-06-01 17:42:02 +0800 CST
  • 2

Host:

Debian 6.0 (squeeze) with qemu-kvm and libvirt from squeeze-backports

ii qemu-kvm 1.0+dfsg-8~bpo60+1

ii libvirt-bin 0.9.8-2~bpo60+2

Has 3TB sata drives with software raid and lvm. It has a sequential write speed of ~140MB/s measured with dd bs=1M count=512 if=/dev/zero of=test conv=fdatasync

Elevator set to cfq

Guest

Debian 6.0 (squeeze)

Uses LVM as storage. Drivers are virtio and cache='none'

Sequential write speed is considerably slower with only 25-50MB/s

Elevator set to noop

I'm kind of running out of ideas for further tweaks but I'm sure that I/O speed should be much faster because many people are reporting almost native performance with lvm.

virtualization linux debian kvm-virtualization libvirt
Martin Hope
Akarot
Asked: 2012-01-10 12:45:34 +0800 CST
  • 5

I have a cluster of about 50 ubuntu nodes which are currently running maverick release. I'd like to upgrade them to oneiric, but I'm having a difficulty choosing the right tools.

I know ubuntu has the 'unattended-upgrade' utility, but it's only meant for security upgrades and cannot switch the whole release. Is there anything similar that can?

For now it seems that the only choice is to use something like fabric/pssh/capistrano and make it run 'do-release-upgrade' on each of the servers. But 'do-release-upgrade' is interactive and requires some input from the user during the upgrade. There doesn't seem to be any --unattended parameter for the 'do-release-upgrade' tool.

What kind of tactics do you use in situations like this?

Thanks!

linux ubuntu cluster fabric
Martin Hope
Akarot
Asked: 2011-03-26 10:37:47 +0800 CST
  • 4

OpenVPN clients work fine when they're started by /etc/init.d/openvpn for the first time, but they can't reconnect if the master server is restarted.

This is the error I get in syslog:

ovpn-openvpn[8113]: Note: Cannot ioctl TUNSETIFF tun: Operation not permitted (errno=1)
ovpn-openvpn[8113]: Note: Attempting fallback to kernel 2.2 TUN/TAP interface
ovpn-openvpn[8113]: Cannot allocate TUN/TAP dev dynamically
ovpn-openvpn[8113]: Exiting

This are the file permissions of tun device:

crw-rw-rw- 1 root root 10, 200 2011-03-24 16:51 /dev/net/tun

If I then restart the client using "/etc/init.d/openvpn restart", they connect normally.

Also, problems only appear when openvpn runs as user 'nobody'. Running as 'root' solves everything but it's not a viable solution.

'persist-tun' option also helps a bit, but not too much. Tunnels still don't last overnight.

Any suggestions?

vpn linux networking openvpn tun