Look when placed against hard disk of general PC, the hard disk applied to the servers has the four following characteristics: Rotational speed of hard drive utilized on the servers is fast, it could reach 7200 or 10000 rev, or perhaps higher; In addition, it configure with a large (generally is 2 MB and 4 MB) write-back cache (no longer has sufficient date, the actual desktop’s hard disc cache is about 64 MB!); The standard access time is shorter; External transfer rate and internal transfer rate are higher, using standard SCSI hard disk for example Ultra Wide SCSI, Ultra2 Wide SCSI, Ultra160 SCSI, Ultra320 SCSI and so on, the results-transfer rate can reach 40 MB and 80 MB, 160 MB, 320 MB per second. Because of the server’s harddrive almost works best for one day without a break, it sustains many workloads. To ensure the disk drive manufacturer all adopts its unique advanced technology to guarantee the security with the data. To prevent the unexpected costs, the server hard disk drive is usually in a position to withstand the impact of the 300 g to 1000 g. Many servers use the SCSI/SAS hard dick with large-data throughput, low-occupancy of CPU (although CPU occupancy of desktop SATA hard disk drive is low, but obviously not on exactly the same class with SAS hard disk). Using SCSI hard disk must with the SCSI connector, some servers motherboard have integrated SCSI connectors, some have a very dedicated SCSI interface card, a SCSI interface card can pick seven SCSI device, this can be are not matched by the IDE connector (an IDE connector are only able to extend two channels, plus they interfere one another seriously). Hot Swap is usually a hard disc installing some supported servers, it might extract or insert a disk if the server doesn't stop, and OS automatically recognizes the modification of disk drive. This technology is vital to the a day non-stop running servers. Certainly, SATA harddrive also provide fractional treatments, as well as the non-critical business, restart the server is apparently cost-effective than hot swapping (hot plug includes a risk of loss data).