WD should be the hard disk of Western Digital. The first four digits indicate the capacity of the hard disk, such as 800, which means 80G. The fifth number stands for the speed and cache of the hard disk, B stands for 7200 rpm, and J stands for 7200 rpm +8M. The last character is the most confusing, indicating the series and interface of the hard disk. B stands for ATA, D stands for SATA 150, and S stands for SA-TA300. For example, CaviarSE products ending in JS or JD, their interfaces are SATA300 and SA-TA 150 respectively (but neither supports NCQ). In addition, the hard disk coding of western language data may also end in KS or KD, which generally belongs to Caviar SE 16 and 16M caches, and supports ASTA300 and SATA 150 respectively, and supports NCQ with 500G capacity. As for SD and YR products, they belong to Cavair RE and Caviar RE2 series for enterprise users, and their caches are 8M and 16M respectively. C, D, E and F are hard disks * * * with four partitions: C, D, E and F.