Accidental Deletes on External Storage: How Volume Protection can Prevent a Disaster

Nathan Williams, iTech Solutions

If you have an IBM SAN (Storwize or FlashSystem family) then you may be familiar with the process of deleting volumes within the storage management GUI. It’s basically as simple as right-clicking on a volume and selecting “delete.” Pretty easy, but as we all know sometimes easy is dangerous. Have you ever considered what would happen if you tried to delete something that might actually be in use? IBM has thought of that, too. The delete process is a one-way trip and there are a couple of checks in place to make sure that you’re paying attention before you commit to something so drastic.

First, the system prompts you to confirm the number of volumes you are trying to delete. This is a simple check that helps catch selection errors. By asking the administrator to confirm that they really did want to delete x volumes, we can be reasonably sure that the action is at least intentional.

Next, the system checks to see if the volumes are still mapped to a host. If they are, a 2nd dialog is tossed up asking the administrator to address the situation. Theoretically, we shouldn’t be deleting volumes that are still being presented to a system as valid storage, but perhaps the host is being decommissioned or there is some other extenuating circumstance so this is again really just a sanity check. A checkbox is provided to allow for an override and force deleting the volumes regardless of their mapped status.

So, thus far we have seen a few checkpoints but in the event that we are mistaken about which volumes we should be deleting or if we are just not paying attention, there really hasn’t been anything to stop us from removing a volume that is actually being used. This is of course not good; deleting a volume out from under your production system is a recipe for a Very Bad Day. Fortunately, there is a way to put one more layer of protection between us and a whole lotta ‘splainin‘. Enter, Volume Protection!

Volume Protection is a feature which will prevent the deletion of volumes which have had recent I/O activity from any host. When enabled, a time limit is specified – essentially a “cool down” period during which the system will not allow a volume to be deleted if it has been used too recently. The time period is adjustable anywhere from 15 minutes to one day and there is no way to override this wait short of disabling the Volume Protection feature entirely. This feature can be configured from within the GUI under Settings > System.

The idea here is that any volume which has been used within the waiting period is considered “active” and should not be deleted, no matter how hard the administrator may try. The timeout ensures that active data is not removed too hastily or by mistake. As an added bonus, the Volume Protection feature actually applies to a number of actions that are not directly associated with volumes. Here’s a full list of actions which will be safeguarded within the Volume Protection time limit:

  • Deleting a volume
  • Deleting a volume copy
  • Deleting a host or a host cluster mapping
  • Deleting a storage pool
  • Deleting a host from an I/O group
  • Deleting a host or host cluster
  • Deleting a defined host port
  • Creating a remote-copy relationship

If you have a SAN, Volume Protection should be enabled and configured appropriately for your environment. This is even more important if you’re a shop that doesn’t make regular changes to your storage configuration, since unfamiliarity can lead to mistakes when you do need to perform maintenance. Check your setup and make sure this is turned on today – it’s easy to do, takes just a minute, and provides a free safety net against a very long fall.

Note: The Volume Protection feature has been available since version 7.4 of the Spectrum Virtualize software, but it is only accessible via command line through version 8.2. New systems delivered at version 8.3 or newer will have the feature enabled by default.

 

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