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April 7th, 2019 22:00
when perccli set jbodwritecache=on, which of RAID Controller cache or HDD cache is used?
Hi, When perccli set jbodwritecache=on, which of RAID Controller cache or HDD cache is used? RAID Controller: H730 with cache and BBU. SAS HDD:Connect to H730 and configured as JBOD. What I want: I want to use the cache in H730 because there is BBU, and disable the cache in SAS HDD. Any way to do this? Best Regards
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Daniel My
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April 9th, 2019 11:00
I went into the lab to test.
Enabling/disabling jbodwritecache is a controller wide settings that affects drive cache on all drives set to non-RAID mode.
So, if your controller is set to RAID mode and you have drives set to non-RAID the cache on the drives will not be used by default. If you set jbodwritecache to on then all drives on the controller in non-RAID mode will have the setting "Non-RAID HDD Disk Cache Policy" set to enabled. This is drive cache, not controller cache. Non-RAID drives will not use controller write cache.
Thanks
Daniel My
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April 8th, 2019 10:00
Hello
JBOD is a mode, so if the controller is in that mode you would use JBOD in commands that state the mode. I don't think the H730 is capable of JBOD mode. The two modes I'm aware of that the H730 supports are RAID and HBA. Controller write caching is not supported on non-RAID drives.
perccli /c0 show jbodwritecache
If you run that command it should state that it is not supported on this controller. If it states something else let me know.
http://www.dell.com/storagecontrollermanuals/
Thanks
wangyugui
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April 8th, 2019 20:00
We can see write cache is enabled when 'jbodwritecache=on', but which of RAID Controller cache or HDD cache is used?
wangyugui
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April 8th, 2019 20:00
[root@T630 ~]# perccli /c0 show jbodwritecache
Controller = 0
Status = Success
Description = None
Controller Properties :
=====================
--------------------------
Ctrl_Prop Value
--------------------------
JBOD Write Cache Disabled
--------------------------
[root@T630 ~]# perccli /c0 set jbodwritecache=on
Controller = 0
Status = Success
Description = None
Controller Properties :
=====================
-----------------------
Ctrl_Prop Value
-----------------------
JBOD Write Cache ON
-----------------------
[root@T630 ~]# perccli /c0 show jbodwritecache
Controller = 0
Status = Success
Description = None
Controller Properties :
=====================
-------------------------
Ctrl_Prop Value
-------------------------
JBOD Write Cache Enabled
-------------------------
[root@T630 ~]# sdparm /dev/sda |grep WCE
WCE 1 [cha: y, def: 0, sav: 0]
[root@T630 ~]# perccli /c0 set jbodwritecache=off
Controller = 0
Status = Success
Description = None
Controller Properties :
=====================
-----------------------
Ctrl_Prop Value
-----------------------
JBOD Write Cache OFF
-----------------------
[root@T630 ~]# sdparm /dev/sda |grep WCE
WCE 0 [cha: y, def: 0, sav: 0]
[root@T630 ~]#
Daniel My
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April 9th, 2019 09:00
That should be a controller command to controller 0 that is in personality mode JBOD. The use of the JBOD command does not appear to be fully documented. I would have to test in the lab to be certain of how it works.
I suggest running these commands:
perccli /c0 show personality
That will show the personality mode that controller 0 is set.
perccli show
That should list your controllers. When you are using /cx it is not specifying a controller. Using something like /c0, /c1, etc specifies the controller number. We have been running commands against controller 0. Several commands will require specifying a controller.
I am also curious what the output of this command is:
perccli /c0 show jbod
Thanks