For FlashArrays with SafeMode enabled additional considerations and planning will be required for the best experience. As the management of storage is done through VASA, the VASA service frequently will create new volumes, destroy volumes, eradicate volumes, place volumes in FlashArray protection groups, remove volumes from FlashArray protection groups and disable snapshot/replication schedules.
For more detailed information on SafeMode with vVols User Guide. Here is a quick summary of recommendations when running vVols with SafeMode enabled on the FlashArray.
- Any FlashArray should be running Purity 6.1.8 or higher when using vVols before enabling SafeMode.
- vSphere Environment running 7.0 U1 or higher is ideal to leverage the allocated bitmap hint as part of VASA 3.5.
- Object count, object count, object count. Seriously, the biggest impact that enabling SafeMode will have is on object count. Customers that want to enable SafeMode must plan to always be monitoring the object counts for volumes, volume groups, volumes snapshots and pgroup snapshots. Do not just monitor current object counts but all pending eradication object counts as well.
- The use of Auto-RG for SPBM when assigning replication groups to a VM should not be used.
- Once a VM has a storage policy replication group assigned, VASA will be unable to assign a different replication group. Plan that once a storage policy and replication group are assigned, that the vSphere admin will be unable to change that with SafeMode enabled.
- Failover replication group workflows will not be able to disable replication group schedules. Nor will cleanup workflows be able to eradicate objects. Users must plan for higher object counts after any tests or failover workflows.
- Environments that are frequently powering on/off VMs or vMotioning between hosts will have higher amounts of swap vVols pending eradication. Should the eradication timer be changed to be longer than 24hr, then they will be pending eradication for longer time. Storage and vSphere admins will have to plan around higher object counts with these environments.
- In some cases, vSphere Admins may want to configure a VMFS Datastore that is shared between all hosts to be the target for VMs Swap.
- When changed block tracking (CBT) is enabled the first time, this will increase the amount of volume snapshots pending eradication. Backup workflows that periodically refresh CBT (disable and re-enable CBT) will increase the amount of this volume diffs that are issued. Pure does not recommend to frequently refresh CBT. Once enabled, CBT should not normally need to be refreshed.
As always, Everpure recommends that customers running VMware to follow our vSphere storage best practices. However, with vVols, there are some specific recommendations and requirements to keep in mind. This is a Summary and quick look at those recommendations, requirements and guidance.