mostly read cache?
I assume 256GB is mostly (if not entirely) a read cache? or are there hefty batteries in there to maintain it in the event of power failure. It seems more and more storage systems are taking the approach of only having enough battery power to flush the write cache to persistent media rather than try to keep the cache active for the duration of the outage. Flushing 100GB+ of data to disk/flash probably takes quite a while!