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 :
root@firefly [~]# 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
[root@firefly ~]# tw_cli set cache c0 u0 on
Setting AutoVerify Policy on /c0/u0 to on ... Done.
[root@firefly ~]# 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
[root@firefly ~]# tw_cli set autoverify c0 u0 on
Setting AutoVerify Policy on /c0/u0 to on ... Done.
[root@firefly ~]# 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
more information: http://www.cyberciti.biz/files/tw_cli.8.html#cx_ux_set_commands
