Write Cache - Cannot Enable


DaMAN

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Ok, have an array in which Seagate 4x ST4000VN000 and 2x ST6000VX0001 models cannot have WC enabled, Ive hunted/youtubed and tried both the SAS(sdparm --set=WCE /dev/sdX) and SATA(hdparm -W 1 /dev/sdX) strings do not work, I can however enable/disable the 4x Seagate ST8000DM004 without issue, all running off the same controller

FCP does warn that WC is disabled, same result plugged into the controller/HBA or direct off SATA/motherboard, no firmware updates detected for the drives if I plugin to a windows host, everything is updated as this array build is a few days old

 

Topology:

Hard Drives

Intel Intel RES2SV240 Expander

LSI SAS 9211-8i flashed to IT mode fw 20 to case backplane

 

Hit a deadend so far

 

Any suggestions people?

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There are several post about write performance drop if disk write cache in disable. I have googling something, may help, but the exe file not come from microsoft, so take your own risk. And I can't confirm the exe file could help or not.

 

https://social.technet.microsoft.com/Forums/windowsserver/en-US/285f8cef-2a6c-4a23-ae12-a6755b2f9407/event-id-32disable-write-caching-on-the-disk

 

Download file

http://thehotfixshare.net/board/index.php?autocom=downloads&showfile=1113

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Ok, googlefu...changed the NCQ of the array drives from 1 to 31 and speed has increased dramatically, doing a clear on 2 drives, gone from 38mb/s to 130mb/s as soon as I made the change, I am a happy camper!, I was about to hit the go button on another HBA controller!

 

Command to change your NCQ level is echo 31 > /sys/block/sdX/device/queue_depth  sdX is your device, echo XX is the level you want to change to

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21 minutes ago, Benson said:

There are several post about write performance drop if disk write cache in disable. I have googling something, may help, but the exe file not come from microsoft, so take your own risk. And I can't confirm the exe file could help or not.

 

https://social.technet.microsoft.com/Forums/windowsserver/en-US/285f8cef-2a6c-4a23-ae12-a6755b2f9407/event-id-32disable-write-caching-on-the-disk

 

Download file

http://thehotfixshare.net/board/index.php?autocom=downloads&showfile=1113

I guess there is more going on, same drive external of array, fast, within array slow, NCQ tweak changed the game for me so far!

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