Is this a memory bottleneck? I think I only have 256 mb in my filers, should I upgrade for better performance?
Its CPU for the writes. I presume OnTap has a lookup cache ala Solaris' DNLC, so more memory should be a boon to the slow lookup times. However, I've never seen sanctioned or non-sanctioned aftermarket upgrades for cpu/ram in any filer (except cpu swaps in the old x86 boxes, IIRC).
The sluggishness is noticed on lookups and read. Mainly because all of our developers have paths on that filer sourced in their profiles in their unix shells (/usr/local/ and home directories for instance) their shells get REALLY REALLY slow all of the sudden.
One approach would be to increase directory caching on the client side. Not very elegant or appliance-like, but it might help. You can also give a shot at using CacheFS's, particurally for that /usr/local mount. Automating cachefs setup w/ automount isn't the prettiest, but doing this for web content breathed life back into my production nfs servers.
This is on my older f720, and I just got a f740. Is it much of an upgrade in CPU?
Its been forever since I've looked at specs, but I believe each step in the 700's included a marginal cpu clock speed bump as well, double the ram (256mb 720, 512mb 740, 1024mb 760), and more PCI (each step down from the 760 progressively carved up the system board w/ a different position for the edge connector).
Can I just swap heads and have a faster filer?
This should work fine (esp given the 700-800 head swap someone just outlined on the list), but I'd wait for a definitive answer from someone bestowed with more clue than myself before trying in production.
..kg..