de-dupe and compression really hammered my system when I enabled these on my NAS4FREE server. In the end I had to switch them off, adding a SSD as cache drive speeds access up tremendously.
I did't have the luxury of a dedicated NAS server, so my NAS4FREE is running as a VM with 4*2TByte drives and 1*32Gbyte SSD directly connected to the NAS VM (you have to do this from the ESX SSH shell). The problem with using 1 SSD is that it is a single point of failure and if your system crashes then you will loose transient data. Likewise with adding a huge amounts of RAM. If this is a critical system then get a UPS and eliminate single points of failure wherever possible.
Just to give you a idea of performance, I'm hosting on my ESX server
1 * NAS4FREE (running ZFS, SMB, APACHE, uPnP, iSCSI and NFS) - 1.5Gbytes - 4CPUs
1 * Server 2012 (running AD, DHCP) - 2Gbytes - 4CPUs
1 * pfsense (running Firewall, rounter, OpenVPN, Internet proxy, harp, tinyDNS) - 1Gbtyes - 4CPUs
the ESX host is:
AMD A10 5800K with 8Gbytes if RAM
USB 8Gbyte memory stick to boot ESX5.5 server
1* SSD 32Gbytes
4*2Tbyte HDDs
1*500Gbyte ESX datastore
3*NICs
Total cost about £400ish
Why AMD A10, it was cheap in the clearance corner
I tend only to use the NAS server as a media server (dlna) in the evenings and in the day as a NFS/iSCSI file share for my test rig. I use Rsync to backup my clients (approx 10 systems and 4 users) every hour (you will need DeltaCopy for Windows clients). Recently I've fired up the Webserver service to host DokuWiki which is proving challenging to get it working as I would like it!
The NAS VM is configured with 4 cores and 1.5Gytes of RAM, I've never seen the VM max'd out (typically 4% per cpu and 600-700Mbytes of RAM) unless de-dupe and compression are enabled. The CPU does peak at 20% when trans-coding HD movies for dlna streaming. But this can be minimized by storing media in a format that is natively supported by most of the dlna clients.
One thing to note is that if you enable power saving on the NAS, it takes 5-10 seconds to bring the ZFS disks online from sleep. The SDD cache in most cases hides this from the users. Also I can't get S.M.A.R.T to work on the NAS with passed through HDD's!
To summaries unless you really plan to hammer your NAS then the options above (Xeon/i5) are really over kill. Unless you plan to use de-dupe and compression, then you will need fast disks as well.
