• Traditional way of implementing storage • Storage is managed by a single host
• Other hosts must access the storage through that single host, over the LAN
Direct-attached external storage
Fibre Channel
SCSI
Tape Device
Direct-attached internal storage
Direct-attached external storage
Direct-attach storage (DAS):
DAS is the traditional storage architecture in which storage devices are directly attached to a server’s I/O bus. It uses a Block I/O architecture. Storage devices can be internal disks or external disk subsystems, typically attached to a SCSI bus. Storage sits “behind” the server; other hosts must access storage resources over the LAN.
DAS Storage that is accessible by or through an individual server Storage is captive to that server spare capacity could not be allocated to another server