1. if we take snapshots on datastores, will IOs be hold during snapshot? is there any snapshot technology involved?
-IO should be quiesced temporarily to allow for resources to have application consistent backups. This uses Vmware tools in some guest OS.
2. we have many datastores (around hundred for one folder on same VCenter), should we create single resource group or split to multiple resource groups? We have a resource group with 30 datastores, it took around 15 minutes to complete the snapshot, just wonder if any Array resource (CPU, memory, cache) will be consumed to impact the array performance?
-Performance on the Array should not be impacted, as the plugin host should only be working with the resources allotted to it. Depending on your needs and circumstances it may be more beneficial to break up the resource groups up further if this is a pain point in the backups. I'm not aware of any rule of thumb for this.
3. is there any easier way to run a VM on demand snapshot instead of create resource group? Resource groups are how the application functions.
-You can add a single VM into a resource group in order to backup a single VM on demand.
REF: https://docs.netapp.com/us-en/sc-plugin-vmware-vsphere/scpivs44_add_a_single_vm_or_datastore_to_a_resource_group.html
https://docs.netapp.com/us-en/sc-plugin-vmware-vsphere/scpivs44_back_up_resource_groups_on_demand.html
4. is there time and space usage difference for an on demand snapshot between a single VM and its datastore?
-Can you elaborate on your question here?
5. we plan to keep one week datastore snapshots, is that a good approach?
-This is dependent on your environment and business needs. it's not unusual for some users to keep snapshots for months depending on circumstance and need.