Tips & Tricks

This page is just a collection of descriptions regarding how to use, configure, maintain, etc.. EVMS on linux.  Basically, if I do something new (to me) with EVMS, I'll jot down a quick note here about how I did it, so I don't have to flounder around the next time the same thing comes up.

Adding a spare to a raid array

Note: this is for a cold spare (i.e. powering-down the system to add the disk).  If your hardware supports hot-swapping disks, knock yourself out.

1. run evms_gui
2. evms may or may not automatically add a storage object to a new disk.  I added a disk that had several existing partitions, and evms was showing a 'DosSegMgr' for each of them.  If that's the case, you need to remove the storage object:
1. select the 'Disks' tab and highlight the new disk
2. from the menu, select 'Actions -> Remove -> Storage Object from Container'
3. you should see the object (disk) listed now under the 'Available Objects' tab
   
3. select the 'Regions' tab and highlight your raid region
4. from the menu, select 'Actions -> Other -> Storage Object Tasks' and select the raid region (md<n>), or, just right-click on the raid object and select 'Add spare object'
   
5. a list of available features to add should appear, and among them should be something like 'add spare', and it will indicate which disk is available
6. select the option to add the disk as a spare to the region
7. from the menu, select 'Actions -> Save', to apply your configuration changes
8. if your raid region was fine, then you're done, and the spare is now available should anything happen to a disk in the array.  If, however, you were adding a new disk because the array was in the 'degraded' state (functional, but no longer redundant due to a failed drive in the array), then as soon as you add the new disk, evms will begin syncing it to the array contents.  You can observe the progress of this process by executing the following from a shell (replace 'md/md0' with your region ID):

• evms_query details md/md0

Querying EVMS

This is useful for getting info from evms while in a shell, so you can compile an evms status report via a script.

• get general evms info:
  

• evms_query info

• get info about a raid region:

• evms_query info md/md0

• get detailed info about a raid region:

• evms_query details md/md0