Slow ssd cache write

[teo85rm]

Hi all,

i'm newer for unraid, and i testing it with trial version v.6.8.3. (I come from OMV).

I have a problem with a slow ssd cache write, i have 2 ssd (1 very old, samsung 840 EVO 256gb, but in discrete condition and 1 new WD 240 green).

I try all solution:

- brtfs cache pool

- only one disk formatted in xfs 

- only one disk formatted in rfs.

 

in all of case my write speed with cache is 22/23 mbs (gigabit network).

i tryed to change my nic from realtek to intel (two nic intel pci express card), but the result is the same.

If do not use the cache ad use only hdd (1 hdd wd green 2tb very old and 1 hdd HSGT hc310 4tb new for parity) the speed in write is 35/40 mbs,  this result returns for disk performance and how unraid works.

The setup is in AHCI in bios:

:~# lsscsi -H
[0]    usb-storage   
[1]    ahci          
[2]    ahci          
[3]    ahci          
[4]    ahci          
~# lsscsi -g
[0:0:0:0]    disk    Kingston DataTraveler 3.0 PMAP  /dev/sda   /dev/sg0 
[1:0:0:0]    disk    ATA      HGST HUS726T4TAL W460  /dev/sdb   /dev/sg1 
[2:0:0:0]    disk    ATA      WDC WD20EARX-00P AB51  /dev/sdc   /dev/sg2 
[3:0:0:0]    disk    ATA      WDC WDS240G2G0A- 0400  /dev/sdd   /dev/sg3 
[4:0:0:0]    disk    ATA      Samsung SSD 840  AB0Q  /dev/sde   /dev/sg4

 

i tryed varius guide with trim the ssds and install plugins.  But now I don't know how to solve,  diagnositcs is in attached.

 

sorry for my english! :)

 

Regards

 

Teo

 

 

nas-srv-diagnostics-20200527-1204.zip

[JorgeB]

1 hour ago, teo85rm said:

If do not use the cache ad use only hdd (1 hdd wd green 2tb very old and 1 hdd HSGT hc310 4tb new for parity) the speed in write is 35/40 mbs,  this result returns for disk performance and how unraid works.

Though better this is still slower than it should be, with just a single data disk Unraid works basically like RAID1, start by running a single thread iperf test to confirm network is working correctly.

[teo85rm]

thanks for reply Jorge, you centered the problem!

For this moment the machine has been moved for maintenance in other room, and not near the switch (probably problem with the cable? need investigation), I put it away, in orgin position and the write speed increase 10/15 mbs.  The performance with or without cache are almost similar, something more without cache but not significant (3/5 mbs).

 

In attach the test with iperf3 from my client pc (in the second i changed the position of machine).

 

Then I did a test  for write/read inside unraid from/to  two shared folder (1 with cache and 1 one not) the speed in write are 140 mbs (no cache) 160mbs (cache).

 

after this result, the problem is not of unraid but of the network, probably my laptop connected via nic, the next steps are testing the netwoks with my client near the switch, and it's possible to change the network conf of unraid with two nic in bonding.

another note: instead I have not noticed variations using the nic realtek or intel.

 

thanks

 

Teo

 

 

 

 

 

test_iperf.txt test_2_iperf.txt