Cache 1GB, 512MB, 256MB: what difference does it make?

Hi forum-members,

I was looking for IBM M5015, but now I can get IBM M5014 (with iBBU) for quite good price. I' ready to go for it, but it has "only" 256MB of cache. I know M5015 has 512MB, and some LSI-models (9270?) even 1GB.

So I want to ask: Does it make a big difference? And if it does, in what scenarios?

BTW, I'd like to use it for moderately loaded ESXi (~20 VMs), 2 arrays: raid5 (4 HDD) and raid1 (2 SSD)...