the primary computer storage medium, which is made of one or more aluminum or glass platters, coated with a ferromagnetic material. Most hard disks are fixed disks, which are permanently sealed in the drive. Removable cartridge disks are gaining in popularity and are increasingly available in more varieties. Most desktop hard disks are either IDE or SCSI. The advantage of SCSI is that up to seven or more devices can be attached to the same controller board. Hard disks provide fast retrieval because they rotate constantly at high speed, from 3,000 to 10,000 rpm., kõvaketas (Hard Disk) on suure mahutavusega (paarikümnest megabaidist mitmete gigabaitideni), kuid üldjuhul mittevahetatav ketas, st. ta on kettaseadmesse sisse ehitatud ja riknemise korral pole "kodustes tingimustes" remonditav. Vajaduse koral vahetatakse ta välja koos kettaseadmega. Kõvaketta eeliseks võib lugeda ka suurt töökindlust