we have 366 GB of fast cache enabled. The array has 270 TB of usable space.

To answer this part

>I still have available memory to add to write cache.  I realized I have disable to change the value. Will this cause any issues? No luns are defined yet on this array.

No it will not cause any issues, Obviously if this array was in production and you had to disable write cache that would have a heavy performance impact, but as you said if the array is still preproduction you should be fine.

Gearoid

Did you install any enablers? The enablers consume memory. Since read cache is disabled it sounds like you enabled FAST Cache on the array.

Thank you Ernes, yes fast cache is enabled.

You are probably following this primus, but just in case here it is again: emc251589

I would still recommend you assign some space to read cache even though FAST Cache is configured. Why? Well, you might not enable FAST Cache on every LUN you create on the array and you want those LUNs to have a little bit of read cache. So disable read and write cache, set the read and write cache and re-enable read/write cache.

Many thanks Gearoid, Dynamox and Ernes!!