Robin AK Posted October 23, 2019 Share Posted October 23, 2019 (edited) Hello, just signed up to say thanks and share my config. I was having similar issues with slow write speeds, around 25 MB/s but on benchmarks it peaks around 200 MB/s Now with disk cache enabled peaks around 190 MB/s both read and write, without using the cache drive and with turbo write enabled. sdparm --set=WCE /dev/sdb From NetData running in a docker container, before the read and write was at 100% utilization. Im using a DELL PERC H330 controller (even updated the firmware from unraid), tested both RAID (Physical disk mode) and HBA mode without any difference. With 4x Dell / Seagate model: ST2000NM0018 Edited October 23, 2019 by Robin AK Added HDD model. Quote Link to comment
sota Posted October 26, 2019 Share Posted October 26, 2019 (edited) Back to it being slow. Had the machine off for a couple days, waiting on some parts to come in. Moving more data on to it, and write speeds are down again to 30MB/s. Did the WCE thing on all drives, no effect. Will try mounting an NTFS disk in a bit, do a test transfer, and see if things change. Local disk-to-disk transfer of a 4GB file resulted in a 168MB/s data rate. cube-diagnostics-20191026-2353.zip Edited October 26, 2019 by sota Quote Link to comment
BRiT Posted October 27, 2019 Share Posted October 27, 2019 Looks like you're having ACPI Errors too. Oct 26 16:12:33 Cube kernel: ACPI Error: SMBus/IPMI/GenericSerialBus write requires Buffer of length 66, found length 32 (20180810/exfield-393) Oct 26 16:12:33 Cube kernel: ACPI Error: Method parse/execution failed \_SB.PMI0._PMM, AE_AML_BUFFER_LIMIT (20180810/psparse-516) Oct 26 16:12:33 Cube kernel: ACPI Error: AE_AML_BUFFER_LIMIT, Evaluating _PMM (20180810/power_meter-338) Oct 26 16:18:02 Cube kernel: ACPI Error: SMBus/IPMI/GenericSerialBus write requires Buffer of length 66, found length 32 (20180810/exfield-393) Oct 26 16:18:02 Cube kernel: ACPI Error: Method parse/execution failed \_SB.PMI0._PMM, AE_AML_BUFFER_LIMIT (20180810/psparse-516) Oct 26 16:18:02 Cube kernel: ACPI Error: AE_AML_BUFFER_LIMIT, Evaluating _PMM (20180810/power_meter-338) Looks like you don't have write cache enabled on some of the drives. Oct 26 16:02:19 Cube kernel: sd 1:0:6:0: [sdg] Write cache: disabled, read cache: enabled, supports DPO and FUA Oct 26 16:02:29 Cube kernel: sdg: sdg1 Oct 26 16:02:35 Cube kernel: sd 1:0:5:0: [sdf] Write cache: disabled, read cache: enabled, supports DPO and FUA Oct 26 16:02:45 Cube kernel: sdf: sdf1 Oct 26 16:02:48 Cube kernel: sd 1:0:4:0: [sde] Write cache: disabled, read cache: enabled, supports DPO and FUA Oct 26 16:02:48 Cube kernel: sde: sde1 Oct 26 16:02:53 Cube kernel: sd 1:0:4:0: [sde] Write cache: enabled, read cache: enabled, supports DPO and FUA Oct 26 16:02:53 Cube kernel: sde: sde1 Oct 26 16:04:12 Cube kernel: sd 1:0:3:0: [sdd] Write cache: disabled, read cache: enabled, supports DPO and FUA Oct 26 16:04:12 Cube kernel: sdd: sdd1 Oct 26 16:04:16 Cube kernel: sd 1:0:3:0: [sdd] Write cache: enabled, read cache: enabled, supports DPO and FUA Oct 26 16:04:16 Cube kernel: sdd: sdd1 Oct 26 16:04:17 Cube kernel: sd 1:0:2:0: [sdc] Write cache: disabled, read cache: enabled, supports DPO and FUA Oct 26 16:04:27 Cube kernel: sdc: sdc1 Oct 26 16:04:31 Cube kernel: sd 1:0:1:0: [sdb] Write cache: disabled, read cache: enabled, supports DPO and FUA Oct 26 16:04:41 Cube kernel: sdb: sdb1 Oct 26 16:08:20 Cube kernel: sd 1:0:1:0: [sdb] Write cache: enabled, read cache: enabled, supports DPO and FUA Oct 26 16:08:20 Cube kernel: sdb: sdb1 Oct 26 16:08:46 Cube kernel: sd 1:0:1:0: [sdb] Write cache: disabled, read cache: enabled, supports DPO and FUA Oct 26 16:08:46 Cube kernel: sdb: sdb1 Quote Link to comment
sota Posted October 27, 2019 Share Posted October 27, 2019 (edited) I'm not sure how to interpret the ACPI errors; keep in mind there's 3 controllers on this machine: CD-ROM SATA, HP B210i (not used), HP P420 (used). And of course the USB slot for the unRAID stick (inside the case.) I re-checked the cache settings and --get says they're all set to enabled. However when I did force it for sdf and sdg and refreshed the log I see an entry each for sdf and sdg saying it's now enabled. Weird. eta: dug more on the ACPI errors... they're nothing to worry about. They're related to HP being HP; see https://www.serveradminblog.com/2015/05/kernel-acpi-error-smbusipmigenericserialbus/ I'll worry about dealing with that later. Edited October 27, 2019 by sota Quote Link to comment
timwf Posted October 9, 2020 Share Posted October 9, 2020 On 7/18/2018 at 12:25 AM, Vexorg said: root@Thor:/etc# sdparm --set=WCE /dev/sdd /dev/sdd: HGST HUS726040ALS214 MS00 this really helps! followed with this command and worked out finally. many many thanks for that! Quote Link to comment
BenW Posted November 5, 2020 Share Posted November 5, 2020 (edited) Could someone help me diagnose slow write speeds on my server? I'm getting about 15-20MB/S, and when copying over multiple small files it takes an extremely long time. I've checked the write cache as per post two, and all seem to be enabled with the exception of the boot flash drive. Diagnostics attached! TIA! edit: UPDATE So I did some more testing, and it appears that the slow write speeds (and read speeds) were due to MacOS - I have two Macs as my main production machines, and a windows box as a fail-over. I tested the windows box and was consistently getting 105ish MB/s read over the network and ~70-80MB write, compared to ~50MB/s read on both Macs and 15-20MB/s write. After some hunting and troubleshooting, I found that MACos SMB implementation is apparently pretty crap, but turning off delayed ACK seemed to fix the issue. To test it (non permanent) in terminal: sudo sysctl -w net.inet.tcp.delayed_ack=0 All of a sudden, I was getting read and write speeds the same as the windows box. This is a MASSIVE improvement!! For anyone that is on MACos and needs a permanent fix, this is what I did: To make the change permanent (requires reboot): Create/edit the file /etc/sysctl.conf Terminal: sudo vim /etc/sysctl.conf Add this line to the configuration file: net.inet.tcp.delayed_ack=0 Save and close file (type “:wq” without quotes, then hit enter) reboot computer Edited November 5, 2020 by BenW Quote Link to comment
adminmat Posted June 8, 2021 Share Posted June 8, 2021 This helped all these years later even in Windows 10. 🍻 Quote Link to comment
TechnoWerk Posted March 25, 2022 Share Posted March 25, 2022 On 7/17/2018 at 6:25 PM, Vexorg said: After a ton of Google-fu I was able to resolve my problem. TL;DR Write cache on drive was disabled found an page called How to Disable or Enable Write Caching in Linux. The artical covers both ata and scsi drives which i needed as SAS drive are scsi and are a total different beast. root@Thor:/etc# sdparm -g WCE /dev/sdd /dev/sdd: HGST HUS726040ALS214 MS00 WCE 0 [cha: y, def: 0, sav: 0] This shows that the write cache disabled root@Thor:/etc# sdparm --set=WCE /dev/sdd /dev/sdd: HGST HUS726040ALS214 MS00 This enables it and my writes returned to the expected speeds root@Thor:/etc# sdparm -g WCE /dev/sdd /dev/sdd: HGST HUS726040ALS214 MS00 WCE 1 [cha: y, def: 0, sav: 0] confirms the write cache has been set Now I'm not total sure why the write cache was disabled under unraid, bug or feature? While doing my googling there was a mention of a kernel bug a few years ago that if system ram was more then 8G it disables the write cache. My current system has a little more then 8G so maybe? this post show how everyone is really excited about this feature. Currently im getting around 40MB/S write speed and i would like to enable this feature either. could you write down all steps? I do not understand where and how i can write this commands down, and how i handle my own HDD/SSD to this command. Quote Link to comment
trurl Posted March 25, 2022 Share Posted March 25, 2022 4 hours ago, TechnoWerk said: Currently im getting around 40MB/S write speed If you are writing to the parity array this isn't unusual and has nothing to do with drive write cache. https://wiki.unraid.net/Manual/Storage_Management#Array_Write_Modes Quote Link to comment
Arend Posted February 13, 2023 Share Posted February 13, 2023 Grand! As i dont have space for a cache drive in my DL60 and use SAS disks this really helped out! Was getting the 40-50mb write over network smb and now its 105mb ish. What i had tho was to add the save prefix as well for it to kick in sdparm --set=WCE --save /dev/sda from https://linux.die.net/man/8/sdparm To set the "Writeback Cache Enable" bit in the current values page: sdparm --set=WCE /dev/sda To set the "Writeback Cache Enable" bit in the current and saved values page: sdparm --set=WCE --save /dev/sda Quote Link to comment
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