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

DRAFT -- Revision 2.0
August 22, 1996Page 54
NOTES:
*1 requires possible removal from rack, opening of the tower or tray, and a
many-step complex procedure
*2 requires a multi-step complex procedure; mechanisms can be easily
removed and replaced from the front
*3 requires quiescence of the application, several LVM commands, possible
slide-out from the rack, opening of the tower or tray
*4 requires quiescence of the application; mechanisms can be easily
removed and replaced from the front
*5 requires a procedure similar to that of on-line or quiescent JBOD
replacement
*6 with LVM mirroring of multiple RAID disk arrays
*7 inherent capability due to mirroring of standalone disks
*8 with multiple disk arrays and PV Links
*9 with V-cable and PV Links
*10 with redundant controller and PV Links
SUMMARY
If it is possible to simplify the myriad of factors associated with choosing the right disk in
an HA environment, one could reduce to the general case by concluding:
If performance is more important than cost and capacity, LVM mirrored
standalone disks (JBODs) are the best choice.
If cost and/or capacity are more important than performance, HADA disk arrays
in RAID 5 are the best choice.