I am become death, destroyer of SANs

Most people want their SAN to keep data around, with maximum resiliency. But what do you do at the end of their lives?

From time to time I get called in to do the opposite of what most people care about from SANs – destroying them. ONTAP has built in sanitization options, which perform a combination of overwrites and zeroing of drives, to enable you to securely erase the drives, and with some NetApp models, like the FAS2240 and FAS255x’s, you can convert them into disk shelves.

Sanitizing all the drives in a controller is usually a two step process – you destroy the existing aggregates, create a new basic system on a small aggregate, then run sanitize on the remaining disks, then repeat, erasing the ones used for the root volume while you’re running the first sanitize.

But there’s an easier way – disable cf, offline all the volumes except vol0, take the system down, boot to maintenance mode, destroy all the aggregates, then reassign all the drives to one controller, and create a two disk RAID4 aggregate using the two drives that were the spares from each controller previously – they won’t have had data on them, so usually no need to sanitize. Boot into ONTAP and run through the initial setup wizard (there’s a bit of hand waving here about the exact process, as it differs between 7.x and 8.x), run the sanitize, and you’re done in a single step.

To do a shelf conversion without a sanitize, similar plan – offline volumes, disable cf, boot to maintenance mode, take ownership of all the drives (using disk reassign to reassign them from their partner), then destroy the aggregates, then remove ownership from all drives and shut the system down. Then, swap the PCM/IOMEs out for real IOMs, and attach as a new shelf. The new system will need to zero the spares before you can use the drives, and it is usually half the speed of doing it from option 4 in the special boot menu (which makes it about 17 hours for 3TB SATA), but the waiting game is all part of systems administration 😉


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