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

DRAFT -- Revision 2.0
August 22, 1996Page 41
Table H: Optimum I/O Environment (Best)
I/O Size Random Random Sequential Sequential
Read-intensive Write-intensive Read-intensive Write-intensive
Small
(1-2 KB)
Standalone / RAID 0 ** Standalone/ RAID 3 *
Mirrored (LVM) Standalone / Mirrored (LVM)*
Standalone / Striped (LVM)**
Striped (LVM)** RAID 0/1
RAID 0 **
RAID 5
Large
(>= 64 KB)
Standalone / RAID 0 ** Standalone / RAID 0 **
Mirrored (LVM) RAID 0/1 Mirrored (LVM) RAID 3
RAID 0 ** RAID 5 RAID 0 **
RAID 0/1
NOTES:
* with HP-UX 10.0 feature of merging sequential small I/Os into a single large I/O
** NOT a High Availability configuration
Table I: Sub-Optimum I/O Environment (Worst)
I/O Size Random Random Sequential Sequential
Read-intensive Write-intensive Read-intensive Write-intensive
Small
(1-2 KB)
RAID 3 RAID 3 RAID 3 *** RAID 3 ***
RAID 0/1 RAID 5
Large
(>= 64 KB)
RAID 3 RAID 3
RAID 0/1 Standalone /
Mirrored (LVM)
NOTES:
*** prior to HP-UX 10.0
HIGH AVAILABILITY (HA) DISK CONSIDERATIONS
When implementing an HA solution, a primary goal is to minimize the number of Single
Points of Failure (SPOFs). To achieve the highest availability, all these SPOFs have to
be prevented. Table J summarizes the SPOFs that apply to disk drives and the
solutions that are available.