1. Midterm

2. Problem 1 Why OK with HTTP 1.0 Why OK with NFS/UDP
LARD or L7: route connection by URL or SLB at SYN
DNS (Akamai): route at connection setup by domain name
Why OK with NFS/UDP
every request/reply an independent packet, so can route these independently
HTTP 1.1 and NFS: persistent connections
can’t route request/reply on the same stream independently
No effect on Akamai
If route requests on connection grain, L7 or LARD will lose locality.

3. Leases 1) overhead vs. recovery time
not callback time (-3)
2) server grabs lease if on wrong side of partition.
reject writes
e.g., timestamp writes and reject at target
3) failover, wait lease interval
clients renew
need failure detector and group membership
could use quorum

4. Large-Scale Web Caching
explain basic mechanism
larger populations for same hit rate, + flatter curve
ignoring deemphasizes benefit of cooperative caching
100% cacheable hit rate with sufficiently large cache
effect of popularity (5 points)
say something about traces (5 points)

5. URL Hashing
LAN
good locality ==> good caching, less storage needed
possibility of unbalance
simple switch
failure/reconfig issue (+ or -)
Alternative: e.g., LARD
WAN
see above
one hop, but no geo-locality (5)
alternative: summary cache