Start from hardware planning. Buy MPE supported disk. Consult with IODFAULT.PUB.SYS file contain supported disks. Verify that you have place for it, free connector on cable, free power connector. Consult with SYSGEN output about avaliable SCSI addresses.
The most quick way to add disk is its "blind" defining prior actual disk adding. Keep existing configuration to be able start with "known good" configuration in case if something will go wrong:
:SYSGEN sysgen> KEEP BCKCFG sysgen> EXIT
You can boot using this config by command ISL> START NORECOVERY CONFIG=BCKCFG
: SYSGEN
SYSGEN version E.05.00 : catalog version E.05.00 WED, SEP 3, 2008, 9:58 AM
Copyright 1987 Hewlett-Packard Co. All Rights Reserved.
**note** Retrieving NMMGR configuration data...
** First level command **
io log (lo) misc (mi) spu (sp)
sysfile (sy)
basegroup (ba) keep(ke) permyes (pe) show (sh)
tape (ta)
clear (cl)(c) exit (ex)(e) help (he)(h) oclose (oc)
redo
sysgen> IO
** IO configurator commands **
aclass (ac) adev (ad) apath (ap) avol (av)
dclass (dc) ddev (dd) dpath (dp) dvol (dv)
lclass (lc) ldev (ld) lpath (lp) lvol (lv)
maddress(ma) mclass (mc) mdev (md) mpath (mp)
mvol (mv) hautil (ha)
clear (cl)(c) exit (ex)(e) help (he)(h) hold (ho)
oclose (oc) redo
io> AP 1/0/0/0.6 ID=PSEUDO
io> AD LDEV=14 1/0/0/0.6.0 ID=ST373405LC CLASS=(DISC,SPOOL)
io> HO
sysgen> KEEP
Reboot system with NORECOVERY option, you should see new device now. Use VOLUTIL to start use new disk