For the highest performance and reliability available today, the Xserve works with next-generation hot-pluggable 15,000-rpm SAS (Serial Attached SCSI) Apple Drive Modules with 73GB or 300GB capacities, offering up to 900GB of SAS storage in three hot-swap hard drive bays.
Overview
The Apple Drive Module (ADM) is a hot-pluggable hard drive in a special drive carrier module designed for easy server upgradeability and maintenance. Apple SAS Drive Modules are available in 73GB or 300GB capacities and operate at 15,000 rpm and are equipped with 16MB of disk cache
SAS (Serial Attach SCSI) hard drives
SAS drives deliver higher sequential performance (up to 125MB/s) and outstanding random access performance for the most demanding applications. Best-in-class mean time between failure (MTBF) ratings means you can trust Xserve to deliver ultimate reliability for critical server environments. SAS drives are ideal for applications requiring the highest performance, fastest random access times, and highest reliability available. SAS drive modules features a point-to-point interconnect to each drive, enabling each drive to be electrically isolated from each other so that drives don't compete for bandwidth, and utilize a protocol that enables fast data transfer to and from the hard drive -- 3.0 gigabytes of data per second.
Software and Hardware RAID options
Mac OS X Server includes AppleRAID, providing RAID 0 and 1 support through software, allowing you to increase either data redundancy or performance. Xserve features on-line rebuilding of RAID 1 volumes and is able to boot from RAID volumes. Choose any combination of mirroring or striping across the three drive bays. RAID configurations require a minimum of two ADM hard drives. For increased protection and performance, add the Xserve RAID card to your Xserve, which provides hardware RAID 0, 1 and 5 with 256MB of cache and a 72-hour cache battery backup.
Apple Drive Module SAS Compatibility
SAS Apple Drive Modules are compatible only with the Intel-based Xserve. For drive module compatibility with other Xserve systems, please see https://docs.info.apple.com/article.html?artnum=107569
