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Poor SSD Write speeds


MBchristoff

Question

Hi Guys,

 

I've been setting up my XPEnology for the past few weeks and noticed that my write speeds went down horribly after enabling SSD-cache.

The transfer starts out at about 1GByte/s (not bit) but goes down all the way to 30MB/s or even lower write speeds, read speeds are fine though.

After trying some diffrent settings and also making a RAID 0,1,5 and basic RAID setup the speed still seemed to stay really poor,..

I blamed the network settings at first but noticed my raid5 3 HDD setup manages to keep a steady 500-600MB/s (Bytes not Bits) while transfering from my pc to the XPEnology.

 

Copying a large file from one SSD to another gave me the same poor performance.

At the Benchmark in the storage manager the SSD read speed caps out at about 550MB/s but the Write caps out at about 30MB/s.

I've tried a different ssd, port, cable and controller so far but nothing seems to help.

 

Booting up Windows and benchmarking the SSD with Crystal Disk Mark gave me about 550/500 Read/Write on both SSDs.

 

I'm using DSM6.1.4-5 on 1.02b with the extra.lmza v4.3 driver package on a SuperMicro a2sdi-h-tf motherboard.

I have come across a couple of seemingly similar cases but these were unsolved or different causes (like SMB and networksettings).

 

Does anyone have a tip for me to try out or could give me some advice?

 

Kind regards,

 

Mike

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On 1/4/2018 at 7:04 PM, MBchristoff said:

 

 

Safe to assume you are using a 10Gbe network here?

When you created your SSD cache you created a 2 SSD Read/Write and only for sequential transfer correct?

Atom CPU (a great atom but still an atom) might be impacting performance, did you monitor CPU while this is happening?

3HDD RAID5 supplies a steady 500-600MB/s? that's not real, must be caching involved.  the most you can hope for in writing to a 3 disk raid 5 array is 2x a single disk, and I doubt you have HDD disks that can go that fast 

my really old agility 3 SSDs five 120 write performance in the DSM write benchmark in my xeon system.

maybe you have an issue with backplane?

 

BTW very cool motherboard! I would love one!

 

  

 

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3 minutes ago, mervincm said:

 

Safe to assume you are using a 10Gbe network here?

When you created your SSD cache you created a 2 SSD Read/Write and only for sequential transfer correct?

Atom CPU (a great atom but still an atom) might be impacting performance, did you monitor CPU while this is happening?

3HDD RAID5 supplies a steady 500-600MB/s? that's not real, must be caching involved.  the most you can hope for in writing to a 3 disk raid 5 array is 2x a single disk, and I doubt you have HDD disks that can go that fast 

my really old agility 3 SSDs five 120 write performance in the DSM write benchmark in my xeon system.

maybe you have an issue with backplane?

 

BTW very cool motherboard! I would love one!

 

  

 

Hi

 

Yes I am using 10Gbe for my network.

 

I tried making a read/write cache with and without the sequential, but even a normal raid 1 or even 0 of 2 ssd's gave me this issue.

The atom did not seem to have a problem with either of the raid setups I have tried.

 

There is some caching involved in my network by the networkcards, the file transfers however were about 40GB/s in size.

I'm using Seagate Enterprise drives wich are rated for 250mb/s+ each.

My now 5 drive raid 5 manages to get between 600 and 800 mb/s depending on the filetype so caching is just a novelty at this point.

 

The ssd's are directly attached to the embeded sata ports using a sata cable, however I did try them using the SAS connectors via a backplane giving me the same results.

 

I must say I'm very happy with the motherboard so far, even though the Atom is not incredibly powerfull it manages to keep up with a some vm's dockers and video encoding.

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I have a lenovo Xpenology system with a 10gig intel 559 based card, xeon 1226v3 CPU, 32GB RAM, and 6HDD (WD RED) RAID5, LSI IT mode HBA (6g SATA/SAS) an well as a real synology 1815+ w 5HDD RAID5. I have not tried adding in SSD cache as my testing (back in 5.x days) showed that adding them in impacted my sequential performance in a negative way.

my Win10 system is a 6700k w 32 GB ram, Intel SSD750 and a samsung 960 evo, and on the same 10gigE intel card.

 

I can do some tests, so you have something to compare to.

 

 

 

 

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My old XPEnology with 5.x did not show any bad speeds either, I don't know if it's due to my hardware or the XPEnology software.

 

Since I just disabled the sequential caching my need to solve this has gone to a lower priority, I originally wanted to use Nvme storage but the current loaders don't support this.

If it's a hassle to switch over your ssd's to the XPEnology in any way don't bother.

I might install XPEnology on another system with a 10Gb port some day and test the speeds there.

 

Thanks for the offer though.

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Seems like the right approach to me. Disable sequential caching till NVME support is available. It should not be too long, as models like the 918+ have nvme caching features. Once that is in Xpenology, you can LACP your 2 links from switch to NAS, and one day be pushing for 2 gigabytes per second transfers! :)

 

 

 

 

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Just now, mervincm said:

Seems like the right approach to me. Disable sequential caching till NVME support is available. It should not be too long, as models like the 918+ have nvme caching features. Once that is in Xpenology, you can LACP your 2 links from switch to NAS, and one day be pushing for 2 gigabytes per second transfers! :)

 

 

 

 

That is exactly what I would like to do. Living the storage dream.

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