VNX2: Hot Spare Policy has been violated though unbound drives are present. (User Correctable)

VNX2: Hot Spare Policy has been violated though unbound drives are present. (User Correctable)

Product:

VNX2 Series

 Issue:

    Hot Spare Policy has been violated but no disk is in faulted state.   
   
    Receiving alert:   
    "7256 Hot Spare Policy has been violated due to insufficient unused disks for hot spare processing"                                                           

 Cause:

 Available unbound drive is a vault drive.   

   
    There are no more Disks for hot spare processing.   
   
    Vault drives are part of RAID group and One of those vault drives has been permanently replaced by another drive due to drive failure. So, Available unbound drive is vault location drive after replacement.   
    For example,   
   
    Drives 0.0.0, 0.0.1, 0.0.2, 0.0.3 are in RAID group 1.   
    Drive 0.0.2 failed and was replaced by 0.0.10. (Copy to Hot Spare)   
    Now RAID group 1 will have following drives : 0.0.0, 0.0.1, 0.0.10, 0.0.3   
    0.0.2 will be permanently swapped by 0.0.10.   
   
    So 0.0.2 will be available as unbound drive after its replacement, which is not a valid drive for hotspare as it is a vault location drive.   
 

Change:

Vault drive which is a part of RAID group was replaced.                                                           

Resolution:

++ If the alert is due to vault drive replacement:   
    Do a copytodisk to original drive (0.0.2) after replacement.   
    This will get back an unbound drive (0.0.10) which will be valid hotspare drive.   
   
    Command to do a copytodisk:   
    naviseccli -h xx.xx.xx.xx -user <username> -password <password> -scope 0 copytodisk 0.0.10 0.0.2   
   
    In general, naviseccli -h xx.xx.xx.xx -user <username> -password <password> -scope 0 copytodisk <permanently_swapped_drive> <original_vault_drive>   
   
    Alert should disappear after this operation as we have sufficient drives to act as hotspare.   
   
    ++ If there are no sufficient drives for processing (1 drive for every 30 drives of same drive type is the recommendation), Add more drives to array to satisfy the hotspare policy.   
    ++ Check the policy to see if it should be adjusted, or add additional disks to the system to satisfy the policy, there are three Hot Spare policies that a user can select for each drive type of storage in the array.                                                           

Notes:

For best practices and hot spare policies, Please refer to document in below link:   
    https://www.emc.com/collateral/software/white-papers/h10938-vnx-best-practices-wp.pdf