hIOmon SSD Performance Monitor - Understanding desktop usage patterns.

[Ao1]

Here I look at the write performance from C drive to E drive.

hIOmon and TerraCopy report more or less exactly the same. Write speeds of ~105MB/s.

Windows shows a transfer speed of 222MB/s, which seems to be reflective of the cache read speed not the write speed.

EDIT: Looking a little more closly Windows reports 1 item remaining with a file size of 29.6MB. That is the exact size of the Write Xfer Max size that hIOmon reports, so it seems that when you copy a file with Windows it is split into smaller file sizes during the copy processes. When using TerraCOPY the file transfer is made in one sequential Xfer.

[Ao1]

This article helps explain the copy process in Windows:

File Cache Performance and Tuning

http://technet.microsoft.com/en-us/l.../bb742613.aspx

1 = The Copy interface copies data from the system cache into an application file buffer
2 = A page fault occurs when the Cache Manager tries to access data not in cache memory
3 = Dirty pages in the system cache are written to disk by lazy write system worker threads Physical disk updates

The CacheSet Utility – A tool to provide a simple control for setting the minimum and maximum system working set size:

http://technet.microsoft.com/en-gb/s...rnals/bb897561

[Ao1]

There was probably a much easier way of do this, but anyway. In the first shot I monitored what occurred during a 4K AS SSD Benchmark. (I disabled the other tests from running). Theory being that this would show the max IOP capability with 4K reads and writes.

The maximum IOP read rate was 5,037, write 9,872.

Next I monitor a couple of hour’s general usage. I ran a SP & MP game and most of the programs I typically use.

The maximum IOP read rate was 1,788, write 236.

Next I update the AV data base and run a full AV scan, without resetting the general use metrics.

The maximum IOP read rate was 3,484, write 375.

It seems that even with an average queue depth of one I can’t get close to using the available read IOP’s capability of my SSD. As for write IOPs….

[One_Hertz]

It seems that even with an average queue depth of one I can’t get close to using the available read IOP’s capability of my SSD. As for write IOPs….

Keep in mind these measurements are in a per second basis. I.e. 5k I/Os served in 0.5s (perhaps that was all which was required) and then 0 i/os in the next 0.5s would show as 2500 IOPs total. This does not necessarily mean that your SSD is doing the best that can possibly be done. Not that I disagree, it is just that your particular test does not prove it.

[Ao1]

Keep in mind these measurements are in a per second basis. I.e. 5k I/Os served in 0.5s (perhaps that was all which was required) and then 0 i/os in the next 0.5s would show as 2500 IOPs total. This does not necessarily mean that your SSD is doing the best that can possibly be done. Not that I disagree, it is just that your particular test does not prove it.

Good point. I already know that most IOPS (from monitoring the percentage FastIOPcounts) are less than one millisecond. The mistake with SSD is to think in seconds. It’s the same with MB/s. For write speeds it’s possible with the X25-M to see 250MB/s for a single I/O write operation when it is done in less than a second. Here is where it would be interesting to see how other SSD’s perform.

What I try to establish above is the percentage of IOPs utilisation compared to what is available.