RAID and Subsystem Architectures
Subsystem Architectures
What type of Storage Device?
Can we use individual disks for our enterprise storage ?
Does an individual disk offer the features we require;
• Resilience
• Scalability
• Performance
Resilience Scalability Performance
Individual Drives
Data loss if drive Limited to individual Limited by individual
fails drive drive
JBOD
Data loss if single Limited by maximum Limited by individual
(“Just a Bunch of
drive fails no of drives in JBOD drives
Disks”)
RAID Array
Protection against Large Arrays can Enhanced by caching
failure of an scale to many 100’s & striping
individual drive of drives
Just a Bunch of Disks (JBOD) storage:
JBODs are storage devices in which multiple disks are attached to a
common I/O bus and appear as individual attached devices to the
network.
JBODs typically do not contain “intelligence.” If RAID is desired, it must
be implemented by software.
JBODs frequently use a Fibre Channel Arbitrated Loop as the array
backplane to which the disks are connected. Commonly there are two
loop ports provided, to allow a secondary loop to be configured, for
redundancy. Some FC disks allow both ports to be used at the same
time but most allow access through only one port at a time.