Samsung SSD 840 PRO - performance degradation

About year ago I wrote blogpost about endurance and performance test of Samsung SSD 840 PRO. Some things has changed, especially firmware of disks.

I performed test on disk with firmware DXM04B0Q. When you want to buy this disk now you probably have firmware DXM05B0Q or DXM06B0Q.

Problem is, both new firmwares has the same performance degradation issue.

Since my first blogpost we bought about 100 disks and after few months we're started observing some problems on database servers. Servers and disks was very slow, we are talking about 10 MB/s continuous write speed.

First of all, we repeat our direct disk test, then we started to test disk with different filesystems.





As you can see on the graph, direct disk test was ok but situation changed rapidly when you create filesystem and start using disk.

So we created filesystem and did some write tests on 10GB file.



Interesting graph, isn't it ?

Especially par of big degradation on the begening every Ext4 test. When we stopped the previous test and format disk to Ext4, we saw bigger performance degradation for some time... (until disk was rewritten once..) and after it, speed explode to the maximum and stay.

I was thinking that something is wrong with our tests or server or something. So we bought Intel DC 3700 SSD and did the same tests.



As you can see, same tests but no interesting performance changes.

 

So be aware which firmware you have and don't upgrade it if you haven't any problems. If you are experiencing some of these issues, try to use Ext4 filesystem, it may help BUT, remember - Fill disk once on Ext4 before you start using it.

 

Note: If you are using LVM (Logical Volume Manager, or simmiliard technology) on your server, Ext4 filesystem probably will not help you.