StoreVirtual 4335 - Questions regarding alarm status and thin provisioning

[robert-ng]

Hi there,

we have two SV 4335 running in a Cluster. The Volumes / LUNs are used as datastores for vSphere 6.5.

Question 1. Alarm Message

In the alarm section there is a ciritical warning:

Event: EID_QUORUM_CONFIG_STATUS_MISSING_FOM_QW 
Severity: Critical
Date and Time: 24.08.17 07:20 Uhr GMT
Component: SAN/iQ
User: Resync
Object Type: Management Group
Object Name: Cluster01-MGMT
Management Group: Cluster01-MGMT
Cluster: Cluster1
IP/Hostname: strnd04
Message: The management group 'Cluster01-MGMT' requires a Failover Manager (FOM) or Quorum Witness (QW). A management group with only 2 storage systems requires 3 regular managers. Add another storage system to management group 'Cluster01-MGMT' and ensure '3' regular managers are started, or add a FOM or QW to management group 'Cluster01-MGMT'.

Does this mean we have to add a FOM, because we have an even number of nodes?

Question 2. Thick vs. Thin provisioning

All of our volumes are currently thick provisioned. Is ist possible to subsequently change these settings to thin provisioning?  If so, can this be done during production hours or do we need a maintenance window?

Thank You in advance. 

[oikjn · Accepted solution]

yes, you need a FOM as the warning states.  Otherwise when you lose one node there is no majority vote anywhere to say "yes we have 51+% of the votes so we are the official cluster and not a split brain"

As for the thick vs. thin, you should definitely be thin provisioned.  There is no significant overhead when changing over, but you may NOT notice a huge difference in space reduction IF your LUNs have been filled up completely at any point in time.  Any areas on the LUNs that haven't been written to will quickly get reclaimed, but those spaces that were written to at any time will remain as part of the thin volume until the SAN gets a TRIM/UNMAP erase command for that block.  In order to enable space reclaimation, you need to select that option in CMC, but AFTER you need to rescan the LUNs on the targets so that they know TRIM is now a supported function and start using it.  In windows if you can manage it, it is generally simpler to disconnect the LUN and reconnect it IF you can find a maintenance window to do so.

[robert-ng]

Thank you @oikjn !

Where can we find a current StoreVirtual Compatibility Matrix? We cannot access 
hpe.com/info/StoreVirtualcompatibility and the version posted here is somewhat older.

[Fran_delaTorre]

Helo Robert,

you can find all Storevirtual matrix at SPOCK:

https://spock.corp.hp.com/