Dell MD3000i slow write speed - cache deactivated

(credits for this article to vmtoday.com, for an article about a similar IBM array, with slightly different commands)

I stumbled across a problem earlier this year with PowerVault MD3000i SAN array and didn't find a specific resolution for this storage, so I though I write about it here so you can solve it easier.

When you buy the MD3000i with only one controller, it deactivates the write cache, becouse the write mirroring feature is enabled (which requires two controllers). The result is that the writing speed is very low and the latency is high.

To activate the cache you need to use the CLI tool provided with the Modular Disk Storage Manager software, which you can find here: C:\Program Files\Dell\MD Storage Manager\client\SMcli.exe. You can first locate the virtual disks that have the cache suspended (Array0 is the name of my array, you should change it to whatever yours is named)

smcli.exe -n Array0 -c "show allVirtualDisks;"
... Write cache: Enabled (currently suspended)
... Write cache with mirroring: Enabled

To disable the mirroring feature and enable caching:

smcli.exe -n Array0 -c "set allVirtualDisks mirrorEnabled=false;"
smcli.exe -n Array0 -c "set allVirtualDisks writeCacheEnabled=true;"

Later edit:

smcli.exe -n Array0 -c "set allVirtualDisks cacheWithoutBatteryEnabled=true;"

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