FreeBSD 7.1 disk performance issue on ESXi 3.5

Sebastiaan van Erk sebster at
Tue Feb 10 03:59:50 PST 2009


I want to deploy a production FreeBSD web site (database cluster, apache 
cluster, ip failover using carp, etc.), however I'm experiencing painful 
disk I/O throughput problems which currently does not make the above 
project viable. I've done some rudimentary benchmarking of two 
identically configured virtual machines (2 VCPUs, 512MB memory, 8GB 
disk) and installed one with FreeBSD 7.1-amd64 and one with Linux Ubuntu 
8.10-amd64. These are the results I'm getting with dbench <n>:

<n>             1               2               4
freebsd         12.0009         13.6348         12.9402         (MB/s)
linux           376.145         651.314         634.649         (MB/s)

Both virtual machines run dbench 3.04 and the results are extremely 
stable over repeated runs.

The virtual hardware detected by the FreeBSD machine is as follows:

mpt0: <LSILogic 1030 Ultra4 Adapter> port 0x1080-0x10ff mem 
0xf4810000-0xf4810fff irq 17 at device 16.0 on pci0
mpt0: [ITHREAD]
mpt0: MPI Version=


da0 at mpt0 bus 0 target 0 lun 0
da0: <VMware Virtual disk 1.0> Fixed Direct Access SCSI-2 device
da0: 3.300MB/s transfers
da0: 8192MB (16777216 512 byte sectors: 255H 63S/T 1044C)

I've also run unixbench (4.1 and 5.1.2) and the performance of the 
FreeBSD machine is horrible compared to Linux on many of the tests, 
though my first guess is that it all comes back down the disk 
performance (on the CPU-only tests the results are about the same).

Online when I see logs of da0 specs via google, they more look more like 
this (much higher transfer rate, and SCSI-n, n>2):

da0: <ATA GB0500C8046 HPG1> Fixed Direct Access SCSI-5 device
da0: 300.000MB/s transfers

Does anybody know how I can get proper performance for the drive under ESXi?


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