Question VPS Disk Speed Using dd

[WebHostingAce]

Hi,

I know dd command is might not be the best way to test hard disk speed.

I have this SSD VPS, When I do a restart it shows over 400 MB/s for couple of hours.

After couple of hours its goes down to under 200 MB/s.

I contacted the support but they ain't giving any direct answer than everything working fine.

Anyone know why its showing over 400 MB/s for couple of hours and then goes under 200 MB/s?

dd command I use,

# dd if=/dev/zero of=test bs=64k count=16k conv=fdatasync

Thank you.

 

[IgorG]

I would suggest you repeat you tests with Bonnie++ - disk and file system benchmarking tool for measuring I/O performance.
Just install it with

# yum install bonnie++

and then run with something like:

# bonnie++ -d /tmp -s 4G -n 0 -m TEST -f -b -u root

Most probably it will give you more relevant results.
Also note, that writing speeds tend to degrade on SSD because of wear-leveling by the SSD controller.