EVA Cache Question

[Stan Reznik]

I'm fairly new to the EVA San Products (coming from the EMC world). We've recently had a 4100 deployed and while setting up vdisks I see that all of them configured for Write-Back caching show the actual caching scheme being Write-Through. Does anybody know what causes this and how to get the system to go into write-back mode?

P.S. This thread has been moved from Disk to Storage Area Networks (SAN) (Enterprise). - Hp forum Moderator

[Mark Poeschl_2]

That does not sound at all normal. I'd open a call with HP.

[Stan Reznik]

The odd thing is that there are no hardware related issues that i can see at all. All items on controllers and enclures check out green in Command View.

[Uwe Zessin · Accepted solution]

When have the vdisks been created and when did you check the caching?

The EVA allocates the disk space and then writes zeroes to this space in the background. I'd assume the disk operates in write-through caching as long as the zeroing runs.

They will automatically turn to write-back later. I've just checked an EVA's event log, but it looks like there is no event loged that signals the end of this operation - there is an event when you change the policy manually, though.

[Stan Reznik]

I think you may really be on to the issue! They have been created recently and the vdisks are quite large. I also see alot of drive activity when the system is idle indicating that it's probably doing the background init!