How to enable write cache for 3ware Raid controller

You can check the current cache status and then enable or disable it using the 3ware command line utility tw_cli. First lets see how we can check the current status :

[email protected] [~]# tw_cli info c0

 

Unit  UnitType  Status         %RCmpl  %V/I/M  Stripe  Size(GB)  Cache  AVrfy
------------------------------------------------------------------------------
u0    RAID-10   OK             -       -       64K     465.641   ON     OFF    

Port   Status           Unit   Size        Blocks        Serial
—————————————————————
p0     OK               u0     233.76 GB   490234752     WD-WCANY3025042     
p1     OK               u0     233.76 GB   490234752     WD-WCANY2790229     
p2     OK               u0     233.76 GB   490234752     WD-WCANY2124533     
p3     OK               u0     233.76 GB   490234752     WD-WCANY2207783

 

As you can see in this case , its a Raid10 array and the write cache is set to OFF i.e. disabled.

Now to enable it, you need to note the controller and unit number so then it can enabled accordingly, in above case our command to enable write cache would be :

 

tw_cli set cache c0 u0 on

 

[[email protected] ~]# tw_cli set cache c0 u0 on
Setting AutoVerify Policy on /c0/u0 to on ... Done.

 

[[email protected] ~]# tw_cli info c0

Unit  UnitType  Status         %RCmpl  %V/I/M  Stripe  Size(GB)  Cache  AVrfy
——————————————————————————
u0    RAID-10   OK             –       –       64K     465.641   ON     OFF    

Port   Status           Unit   Size        Blocks        Serial
—————————————————————
p0     OK               u0     233.76 GB   490234752     WD-WCANY3025042     
p1     OK               u0     233.76 GB   490234752     WD-WCANY2790229     
p2     OK               u0     233.76 GB   490234752     WD-WCANY2124533   
p3     OK               u0     233.76 GB   490234752     WD-WCANY2207783 

 

autoverify attribute enables the autoverify attribute on the unit that is to be created.

To enable Avrfy option

 

[[email protected] ~]# tw_cli set autoverify c0 u0 on
Setting AutoVerify Policy on /c0/u0 to on ... Done.

[[email protected] ~]# tw_cli info c0

Unit  UnitType  Status         %RCmpl  %V/I/M  Stripe  Size(GB)  Cache  AVrfy
——————————————————————————
u0    RAID-10   OK             –       –       64K     465.641   ON     ON

Port   Status           Unit   Size        Blocks        Serial
—————————————————————
p0     OK               u0     233.76 GB   490234752     WD-WCANY3025042
p1     OK               u0     233.76 GB   490234752     WD-WCANY2790229
p2     OK               u0     233.76 GB   490234752     WD-WCANY2124533
p3     OK               u0     233.76 GB   490234752     WD-WCANY2207783

 

 

As you can see the write cache is enabled now, similarly you can disable the write cache using below command :

tw_cli set cache c0 u0 off

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