Choosing the Right Disk Technology in a High Availability Environment DRAFT Version 2.0, August 1996

DRAFT -- Revision 2.0
August 22, 1996Page 42
Table J: Solutions to Disk Single Points of Failure
SPOF JBODs or HASS with LVM RAID Disk Arrays
Mirroring
Disk mechanism Mirror to different disk Use RAID level 1, 0/1, 3
mechanism or 5 in HADA, FLDA or
SCSI DA
Disk Power Supply Mirror to disk in different Use HADA, AutoRAID or
tray or tower Symmetrix with redundant
power supply option
Power Source Mirror to disk in different
tray or tower; HASS has 2
power cords in one chassis
No Solution except for
AutoRAID which has 2
power cords in one chassis
Disk Cooling System Mirror to different disk Use HADA, AutoRAID or
mechanism Symmetrix which have
redundant cooling system
Disk or Array Controller Mirror to different disk Use HADA, AutoRAID or
mechanism Symmetrix
Cable from SPU Mirror to disk on different Use HADA, AutoRAID or
interface Symmetrix with PV Links
(two F/W SCSI interface
cards)
Computer Interface Mirror to disk on different Use HADA, AutoRAID or
interface Symmetrix with PV Links
(two F/W SCSI interface
cards)
DECISION CRITERIA
The major factors that should be considered in deciding the appropriate disk technology
are:
on-line failed disk replacement
the need for data redundancy
the need for double data redundancy
the need for continuous data redundancy
purchase cost
footprint