Benchmarking VMs shows impossibly high disk read speeds

[oakleeman]

I have something weird going on. Have a Win7 VM with the OS drive on a qcow vdisk on local storage. Have a second qcow vdisk on a NFS share and a third vdisk on an iSCSI LVM. Using iometer in an attempt to benchmark NFS vs iSCSI performance. With iSCSI I can see it both reading from & writing to my SAN but with NFS I can only see it writing…..there appears to be no reads on the SAN.

When I attempt to benchmark vdisks stored on the local storage I also get impossible read speeds.

Is there some sort of disk caching going on? I have each hard disk set to "Default (no cache)" under the cache setting.

 

[oakleeman]

Found a thread asking for the following but didn't want to hijack theirs.

root@pxm1:~# cat /etc/pve/qemu-server/100.conf 
boot: cdn
bootdisk: sata0
cores: 1
ide2: none,media=cdrom
memory: 2048
name: win7
net0: e1000=C2:8B:18:DA:13:46,bridge=vmbr0
ostype: win7
sata0: local:100/vm-100-disk-1.qcow2,size=32G
sata1: hpmicro-sata-100-lvm:vm-100-disk-1,size=32G
sata4: hpmicro-nfs:100/vm-100-disk-1.qcow2,size=32G
sockets: 1

root@pxm1:~# mount
/dev/mapper/pve-root on / type ext3 (rw,errors=remount-ro)
tmpfs on /lib/init/rw type tmpfs (rw,nosuid,mode=0755)
proc on /proc type proc (rw,noexec,nosuid,nodev)
sysfs on /sys type sysfs (rw,noexec,nosuid,nodev)
udev on /dev type tmpfs (rw,mode=0755)
tmpfs on /dev/shm type tmpfs (rw,nosuid,nodev)
devpts on /dev/pts type devpts (rw,noexec,nosuid,gid=5,mode=620)
/dev/mapper/pve-data on /var/lib/vz type ext3 (rw)
/dev/sda1 on /boot type ext3 (rw)
fusectl on /sys/fs/fuse/connections type fusectl (rw)
/dev/fuse on /etc/pve type fuse (rw,nosuid,nodev,default_permissions,allow_other)
beancounter on /proc/vz/beancounter type cgroup (rw,name=beancounter)
container on /proc/vz/container type cgroup (rw,name=container)
fairsched on /proc/vz/fairsched type cgroup (rw,name=fairsched)
10.11.200.19:/mnt/sata01/nfs/pmx on /mnt/pve/hpmicro-nfs type nfs (rw,vers=3,addr=10.11.200.19)

root@pxm1:~# cat /etc/pve/storage.cfg 
dir: local
path /var/lib/vz
content images,iso,vztmpl,rootdir
maxfiles 0


nfs: hpmicro-nfs
path /mnt/pve/hpmicro-nfs
server 10.11.200.19
export /mnt/sata01/nfs/pmx
options vers=3
content images,iso
maxfiles 1


iscsi: hpmicro-sata-100
target iqn.2011-03.hpmicro.learnlab.local.istgt:sata-pmx-100
portal 10.11.200.19
content none


iscsi: hpmicro-sata-200
target iqn.2011-03.hpmicro.learnlab.local.istgt:sata-pmx-200
portal 10.11.200.19
content none


lvm: hpmicro-sata-100-lvm
vgname hpmicro-sata-100-lvm
base hpmicro-sata-100:0.0.0.scsi-330000000a925539c
shared
content images


lvm: hpmicro-sata-200-lvm
vgname hpmicro-sata-200-lvm
base hpmicro-sata-200:0.0.0.scsi-3300000009d999846
shared
content images