Recently we implemented FAST and FAST Cache in our CX4-480.
I have a question about the percent full treshold on storage pools. The treshold is set at 70%, so whenever we hit it, we will be alerted.
That's really nice. But I assume I can use more than 70% of the storage pool. At which level I can expect the performance will be impacted?
Are there any rules of thumb for it?
Performance impact will depend less on your pool capacity utilization and more on whether you are using thin LUNs or thick LUNs. You can read through the Virtual Provisioning whitepaper on Powerlink to understand how thin and thick LUNs work.
You should try and keep the pool utilization below 90%. As it gets closer to full there is a chance that new data will have to be allocated to suboptimal locations. This would occur more often with Thin LUNs as opposed to Thick LUNs though.
Richard J Anderson
Thx for your answer...
When migrating existing luns to the newly created pool, I also see that utilization of the fibre channel disks won't exceed the 90%. I expected therefore that 90% is almost the limit...
We don't create thin luns at the moment, so I don't have worries about them.