This post is more than 5 years old
8 Posts
0
22529
Slow writes PERC H700 and Samsung 850 PRO SSD
I've seen several posts regarding this, but haven't seen a solution.
I have some R710 servers with H700 controllers. I've installed Samsung 1TB 850 Pro SSDs and seeing very slow write performance compared to other SSDs tested within a same box, just slow in general. Samsung SSDs are doing ~500 MB/s in both directions when connected to standalone desktop, but ~500 MB/s read and ~45 MB/s writes when connected to a server.
1. 1x SSD in RAID 0 - No redundancy, just to test performance. I've tried every combination of write-back cache setting and read ahead setting possible (enabled, disabled) and never got more than ~45 MB/s writes.
2. 6x SSDs in RAID 5 with all possible combinations of write-back cache never getting more than ~110 MB/s writes.
3. 6x SSDs in RAID 10 again all possible settings of write-back cache - ~140MB/s.
Lastly I've installed 120 GB Intel SSDs and got over 400 MB/s in both directions regardless of the RAID or caching.
What is the problem with H700 controllers and Samsung SSDs? Does anyone know how to fix it?
Any other R710 compatible controller that don't have this problem? JBOD capable, maybe? I've also tried an off the shelf PCIe controller without any luck (backplane compatibility issues or some sort)
Thanks in advance.
P.S.
Controller is on a latest firmware along with BIOS and all the other components. Used Dell repository manager iDRAC discovery and bootable ISO to update everything.
Samsung SSDs are on a latest firmware as well.
Anonymous
5 Practitioner
5 Practitioner
•
274.2K Posts
0
August 25th, 2016 13:00
Hello.
The Samsung 850 Pro SSDs are not validated or certified to work with Dell controllers and as such there is a communication mismatch between the drives and the controller at the firmware level. As a result, you are bound to realize unexpected poor Read and Write performance regardless of controller cache settings. Consider using Dell certified drives.
Thank you.
IPodgorny
8 Posts
0
August 26th, 2016 18:00
I don't want to be rude or anything, but the drive is sold through Dell. I've searched all over, but couldn't find H700 dive compatibility sheet. On the other hand it may be cheaper to change server chassis than to replace almost $4k worth of drives per server. Thanks for prompt response though :)
Dev Mgr
9.3K Posts
0
August 26th, 2016 20:00
Just because Dell sells an SSD on their website (for use in a laptop or desktop), doesn't mean it will work perfectly in a server using a hardware raid controller.
Here you can find a list of drives (including some SSDs) certified to work properly in an R710 with a PERC H700: http://accessories.us.dell.com/sna/category.aspx?c=us&l=en&s=bsd&cs=04&category_id=2999&mfgpid=202470&chassisid=8796&stype=7&Tab=Parts.
You can also look on Ebay for some more affordable options. Recently a large supply of Intel S3710 400GB SSDs that came from Dell R730 servers came onto the market and can be picked up on Ebay for around US$200 each (very decent price for this model SSD).
JacquesAssert
41 Posts
0
February 23rd, 2018 14:00
Based on the last comment in the thread below (by sysaxe) the slow speed is due to a disabled disk cache.
https://www.reddit.com/r/homelab/comments/3s5szs/t610_w_perc_h700_raid_controller_ssd_options/