Hi there,

We have two Compellent SANs located at different datacentres.  The datacentres run as active/active. SAN1 replicates volumes to SAN2 and vice-versa.  Now this all works fine, but the issue we have come across is as follows:

DC1 has volumes presented to our VMware infrastructure.  On there we have VMs that are protected by SRM.  The volumes at DC1 has some data on Tier 2 and some on Tier3.  Over time with replication running to DC2 with the recommended storage profile the majority of the replicated volumes end up on Tier 3.  Mainly due to data progression running against the replicated volumes and the data not being "active" it is moved down the tiers.

The problem arises in case SRM needs to be invoked.  Tier 3 is only rated for around 2000 IOPS.  When SRM kicks in and mounts the replicated volumes to the VMware infrastructure at DC2, because the majority of the data sits on Tier 3 which is just too slow and makes the VMs unusable.

As mentioned the DCs run as active/active so we have the same issue in reverse from DC2 to DC1.

So in order to get around this issue we've had to force the replicated volumes to Tier 2.  So what we end up with is the day-to-day volume sits on Tier 2 and 3, but the replica sits at Tier 2 at the other DC. This is chewing up a lot of valuable Tier 2 storage.

Now I realise we could purchase more Tier 3 storage to increase the IOPS capacity, but what would be better is to make data progression aware of what tier the source volume has its data.