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

Table L: Detail of Configurations Compared in Table K
Configuration Qty Product # Price each Total Price
DRAFT -- Revision 2.0
August 22, 1996Page 48
C
RAID 1
HADA Arrays
4 A3232A 15,000
4 #320 26,265
4 #421 2,000
4 #532 10,160 213,700
2 28696A 1,295 2,590
2 A1897A 2,450 4,900
221,190
D
RAID 5
SCSI DAs
8 C2440JZ 23,000 184,000
3 28696A 1,295 3,885
2 A1897A 2,450 4,900
192,785
E
Independent
Mode SCSI
DAs
16 C2439JZ 18,000 288,000
16 C2431A 4,300 68,800
6 28696A 1,295 7,770
4 A1897A 2,450 9,800
374,370
Performance
Performance of the disk subsystem is a complex subject and was discussed in
the section on performance. Remember that RAID often , but not always
degrades the performance of the disk subsystem. Factors which affect
performance of the disk subsystem are:
read versus write intensity
volatility of the data (update or insert versus read-only)
random versus sequential access (OLTP vs. DSS)
I/O size
RAID level chosen
whether LVM mirroring is used
the use of multiple controllers for redundancy and performance.
Backup strategy
The application together with business requirements determine whether an on-
line backup can be used. On-line backups are usually done on the same system
that runs the application. Not all applications provide the facility for a consistent