For many years, The Mail Archive has run with a high replication factor for storage - usually 7X. This helps with performance; more drives help serve more requests. It helps with reliability; disk failure is no big deal when there are many more just like it. And we splice full backups right off the replication set with no downtime. For the record, we've had 5 disk failures over the last 4 years without causing any problems.
Two weeks ago we added a new replica, using solid state drives instead of spinning magnetic disks. This is performing brilliantly. We read almost entirely from the solid state drives, which serve data about 10 milliseconds faster. Load dropped from about 7 to 2 on the primary computer, since it no longer waits on the storage system. Batch operations like site map generation are much faster. We should be able to handle significantly more traffic. Best of all, we still retain the safety benefits of replication to low cost magnetic disk. It used to be that The Mail Archive replaced its computer setup every year. This setup is definitely the exception; I'm really impressed with how well the generation 8 server has held up, and how easy it was to get a dramatic increase in performance just by swapping out some parts. In summary, things are alive and well. -Jeff
