topic why read IOPS are more when measured after erasing the SSD in Archive

why read IOPS are more when measured after erasing the SSD

idata — Mon, 02 Aug 2010 19:21:02 GMT

Hi,

I am trying to measure performance of Intel X25-V SSD. I am getting rand read IOPS ~47K after erasing the SSD. But after doing few write, rand read IOPS drop down to 23.6K (Intel's benchmark says 25K). What could be the reason for getting more read IOPS after erasing the SSD.

Thank you in advance.

Regards,

Ramu

Re: why read IOPS are more when measured after erasing the SSD

idata — Tue, 03 Aug 2010 14:08:59 GMT

It's weird that reads should degrade. What benchmark programme are you using? For a quick and accurate benchmark I use AS SSD Benchmark.

http://www.alex-is.de/PHP/fusion/downloads.php?cat_id=4

Are you running AHCI or IDE?

http://communities.intel.com/thread/14613?tstart=0

Re: why read IOPS are more when measured after erasing the SSD

idata — Tue, 03 Aug 2010 17:47:51 GMT

My guess: assuming the benchmark writes a file to the drive first, and then reads it back to measure IOPs, then the file may be more optimally placed when written to an empty disk compared to written to a used disk. I say this because my understanding is that the flash is connected to the controller via multiple channels and performance is somewhat dependant on the number channels that can be used simultaneously.

Re: why read IOPS are more when measured after erasing the SSD

idata — Tue, 03 Aug 2010 17:54:59 GMT

Access time should be more or less irrelevant to where the data has been written. My guess is that the benchmark is giving a false reading when the drive is fresh.

There are some good benchmarks to compare performance here:

http://www.xtremesystems.org/forums/showthread.php?t=245120