Almost all the servers in the farm are blade servers, which give 50 % higher density, with less power consumption, and more efficient cooling than standard servers. Older servers models have 8 GB RAM; newer ones are quad cores with 16 GB, and use SAS drives, instead of the SATA drives in the older blades.
There are 1500 Linux servers in DreamWorks’ employ, and none of them rely on connected un-interruptable power supplies (UPS). But that makes sense: This is disposable computing, and any data accumulated is rendered moot by the next rendering. So, the blades of the render farm are only protected by surge suppressors. There is no need to save the hard drive information; if a few hard drives fail in the farm, there is no noticeable loss because the missing data is recalculated by other systems. Any missing data, especially only an hour or two worth, is easily covered by some of the other computers, which pick up the slack. Thus, there is no need to back up currently rendered information. Think grid computing. DreamWorks replaces a few to 10 hard-drives every month.
After DreamWorks finishes production, the film content is moved to second tier and near line storage. Once a final rendering is completed, data is moved to a storage area network where it is protected by at least RAID Level 6 (RAID 6 is a striped set where data is distributed across multiple drives, with two parity drives). The data is also replicated to a remote site. Content for television commercials is moved to far line storage, so it can be recalled for various markets.