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Sporadic input / output error — x86-64 linux guest
** Setup: **
→ Host
Qemu version 2.4.0.1
Linux: 4.1.1 (Debian 8.2, GCC 4.9.2, x86_64)
filesystem ext3 and ext4
→ Guests (3 VMs)
architecture x86_64, Linux 3.16.0-4-amd64 (Debian 7.6)
virtual disk qcow2, uncompressed
guests filesystem ext3
virtual disks size: VM1: 3GB, VM2: 5GB, VM3: 250GB
→ Network
bridge (br0) and tap interfaces.
** Command line **
For all 3 VMs, the command line is similar to the following. Only RAM size and ID ("109") are changed.
/usr/local/bin/qemu-system-x86_64 -hda /media/raid1/qemu-109 -m 8G -smp 4 -enable-kvm \
-netdev bridge,id=br109 -device virtio-net-pci,netdev=br109,id=nic0,mac=00:00:00:00:01:09 \
-k it -daemonize
** Problem **
Sporadic, unexplained input output error.
When I try to SSH to one of the instances, most of the times everything just works fine. Some other times, the SSH connection can be established, but as I interact with the guests via SSH (ls, cd, top) the guest reports "input / output error" on the SSH console. Sometimes, the SSH daemon on the guest answers "/bin/bash input output error". Sometimes the SSH client answers that the connection has been dropped by the host.
When this happens, the web services I run on the VMs get unreachable, the VMs themselves are unreachable/unusable via SSH as described, and after killing the relative qemu processes and restarting the VMs, no recent logs are registered on /var/logs, arguably since the time of the crash.
This only happens to one VM at a time, independently. The other VMs appear to run fine when one VM encounters the problem.
I which instructions to further debug this.
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