8-STABLE Slow Write Speeds on ESXI 4.0

[Ivan Voras]

On 7.8.2010 3:21, Joshua Boyd wrote:
> Hello,
> 
> I'm experiencing slow write speeds on 8-STABLE running on an ESXI 4.0
> server, despite whatever tunables I've thrown at it. Read speeds are slower
> than they should be, but acceptable. Note, this is a thick provisioned disk,
> not thin.
> 
> Speeds on Windows hosts are as expected for an MD3000 DAS, 250MB/s or so.
> 
> [root at git ~]# dd if=/dev/da0 of=/dev/null bs=1M count=500
> 500+0 records in
> 500+0 records out
> 524288000 bytes transferred in 3.304514 secs (158658118 bytes/sec
> 
> [root at git ~]# dd if=/dev/zero of=/var/testfile bs=1M count=500
> 500+0 records in
> 500+0 records out
> 524288000 bytes transferred in 52.083421 secs (10066313 bytes/sec)

I assume you are using UFS and SU? What tunables have you tried?

It's unlikely they will help, but try:

vfs.read_max=32

for read speeds (but test using the UFS file system, not as a raw device
like above), and:

vfs.hirunningspace=8388608
vfs.lorunningspace=4194304

for writes. Again, it's unlikely but I'm interested in results you achieve.