Disk performance on ESXi with FreeBSD 7.1

[Sebastiaan van Erk]

Hi,

I'm running FreeBSD on ESXi but I'm having serious issues with disk 
performance, and I'm wondering if it might have something to do with the 
scsi driver (or the virtual hardware not returning proper values for its 
capabilities or something)..

I have both a FreeBSD-amd64 and Linux Ubuntu 8.10-amd64 virtual machine 
(8GB disk, 512MB RAM, 2-CPU) and run dbench on both of them. The linux 
machine is out of the box, not optimized for vmware, 
VMI/paravirtualization is off, as is VMotion. The results for dbench <n> 
are as follows:

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

Thus there is approx a factor 30 difference for dbench 1, and I cannot 
imagine linux being that much faster just due to some performance tuning 
kernel parameters.

I tried both the VMware LSI Logic controller and the BusLogic 
controller. Here is the relevant dmesg output of both:

LSI:
mpt0: <LSILogic 1030 Ultra4 Adapter> port 0x1080-0x10ff mem 
0xf4810000-0xf4810fff irq 17 at device 16.0 on pci0
mpt0: [ITHREAD]
mpt0: MPI Version=1.2.0.0
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)

BusLogic:
bt0: <Buslogic Multi-Master SCSI Host Adapter> port 0x1060-0x107f mem 
0xf4810000-0xf481001f irq 17 at device 16.0 on pci0
bt0: BT-958 FW Rev. 5.07B Ultra Wide SCSI Host Adapter, SCSI ID 7, 192 CCBs
bt0: [GIANT-LOCKED]
bt0: [ITHREAD]
da0 at bt0 bus 0 target 0 lun 0
da0: <VMware Virtual disk 1.0> Fixed Direct Access SCSI-2 device
da0: 40.000MB/s transfers (20.000MHz DT, offset 15, 16bit)
da0: 8192MB (16777216 512 byte sectors: 255H 63S/T 1044C)

Something that I noticed was the extremely slow transfer rates mentioned 
with the da0 device.

When I'm running dbench the server is not very busy:

CPU:  0.2% user,  0.0% nice,  6.4% system,  0.7% interrupt, 92.7% idle
  1172 root        1  -8    0  4604K  1228K biowr  1   0:41  4.98% dbench

I really want to get this working because I want to run a big production 
site on FreeBSD. But currently the disk speed is just unworkable.

I was wondering if anybody had any ideas about how to get proper disk 
speeds on FreeBSD, making it a viable guest operating system.

If any other info is needed, I'm willing to invest quite some time to 
provide it!

Regards,
Sebastiaan
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