Near-line storage is used by corporations, including data warehouses, as an inexpensive, scalable way to store large volumes of data. Near-line storage devices include DAT and DLT tapes (sequential access), optical storage such as CD-ROM, DVD and Blu-ray, Magneto-Optical which utilize magnetic heads with an optical reader, and standard also slower P-ATA and SATA hard disk drives. Retrieval of data is slower than SCSI hard disk which is usually connected directly to servers or in a SAN environment. Near-Line implies that whatever media the information is stored on, it can be accessed via a tape library or some other method electronically as opposed to off-line which signified some human intervention is required, such as retrieving and mounting a tape, etc. Near-line can be slower, but the type of data (historical archives, backup data, video, etc.,) dictates that the information will not require instant access and high throughput that SAN and SCSI can provide and is less expensive per byte.