[Xen-API] NFS Storage Performance on XCP

[ND KK <k110168@xxxxxxxxx>]

Hi All,

I have a problem on NFS storage performance in XCP 1.1
I have run several tests, with commands like this. I average over three tests with the same command:
Write: dd if=/dev/zero of=./test1 bs=4M coubt=1024 oflag=direct
Read: dd if=./test1 of=/dev/null bs=4M iflag=direct

Case 1 :

Storage Server - CentOS 5.6:
2 * 2TB SATAII  7.2Krpm HDD in RAID1 for System
12 * 2TB SATAII  7.2Krpm HDD in RAID10 for NFS
10 Gigabit Ethernet (I have tested it by iperf, throughput = 971 MB/s)

Jumbo frames at 9000 bytes are enabled  (I have tested, this's work) 

The performance on storage (local)  R：650(MB/s)  W：478(MB/s)
The performance on XCP Host (dom0)  R：382(MB/s)  W：466(MB/s)
The performance on VM - CentOS (domU)  R:261(MB/s)  W：364(MB/s)

Case 2 :

Storage Server - Nexenta:
2 * 2TB SATAII  7.2Krpm HDD in RAID1 for System
5 * 2TB SATAII  7.2Krpm HDD in RAID5 for NFS
10 Gigabit Ethernet

Jumbo frames at 9000 bytes are enabled 

The performance on storage (local)  R：3.2(GB/s)  W：2.6(GB/s)  <- cache, can't use dd iflag/oflag=direct on Nexenta
The performance on XCP Host (dom0)  R：753(MB/s)  W：824(MB/s)
The performance on  VM - CentOS  (domU)  R:406(MB/s)  W：442(MB/s)

Why the performance  on VM slow than Host(dom0) so much?

Is't blktap2 problem? or nfs mount options? (If it's NFS mount options, why domU slow than dom0 so much?)

Thanks!

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