For DR7 and beyond these will be Quad (4-core) CPU servers. You don't need to have RAID10, since you may not need that redundancy level for a mirror site, however it is recommended so you do not have to download the data again in case of a disk failure. You will need 3+ TB (and 4+ TB or more if you're planning ahead for DR7 and beyond). This is for only the Best database. Currently mirror sites do not keep a local copy of the Target dataset.

We generally recommend that the Web server and DB server be separate boxes, especially if you're supporting a large user community (100 or more). For the webserver, any Windows box with Windows Server 2003 and IIS (preferably IIS 6 or later) running on it will do. If you plan to support the CasJobs or ImgCutout services, you will definitely need a separate webserver with ASP.NET v2.0 or later installed on it.

For our production cluster we also have 2-3 db servers per release, so that the public, collab and astro user levels can be adequately supported and skyserver and casjobs queries can be load-balanced on different boxes. For a mirror site, you will not need that level of performance unless you also plan to support multiple levels of access for a large user community. The current configuration for multiple release support at FNAL is shown in Figure 1. The hardware configuration and load balancing for CasJobs is shown in Figure 2.

Figure 1. Hardware configuration at FNAL (FermiLab) for SDSS Servers.

Figure 2. Hardware configuration and load balancing for CasJobs queries.