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Note 1613.0            ramdisk(fddriver) & shadowing(hbs)             15 replies
TKTVFS::SHINOSAKI                                    76 lines  25-OCT-1993 03:12
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subj:	ramdisk (fddriver) to support vms level-ii volume shadowing.

	Hi, interests

	To introduce shadowed fast disk in our environment, I updated
	memory oriented psuedo disk driver, fddriver (ramdisk) which
	based from toolshed. It running on our primary and secondary
	vcs engines. thier basic characteristics are;
	 o vms t6.1-5vh (ft2) with motif 1.2
	 o vaxstation 4000-60 16mb (rz57x2)
	 o vaxstation 3100-38 32mb (rz56x1,rz23x2 for striping set)

	I had tried to introduce DECRAM T2.0 product first, however
	it dose not work I expected  even if after bug fixed (I gave
	up since I never heard it support vms6.1).  therefore, I'm
	waiting for 2.0 formal release version.
	For the time being, as temporaly solution, traditional fddriver
	from toolshed is updated to supprt hbs environment instead of
	decram product to meet our need.
	I posted its code set (all codes imbeded in a procedure) here,
	next reply of this note entry for your interest.

	How to obtain and build image
	-----------------------------
	Extract next reply of this note entry, and excute imbeded third
	procedure, build.com (standard vms installation kit is unavailable).
	 $ @build.com
	Thus, three images fddriver.exe,fd$setchr.exe and fd$startup.com
	will be created in your current default directory.
	To move images to system directory, SYS$COMMON:[SYS$LDR] and
	SYS$COMMON:[SYSMGR], issue previous dcl command again with
	"install" string in parameter-1.
	 $ @build.com			! create images
	 $ @build.com install		! move images to system directory.

	Using image
	-----------
	Bellow describe differences from traditional fddriver in toolshed.

	<device type>
	To meet 6.0 initialize command, device type changed from dt$_rl02
	to dt$_ram_disk. However, current version of vms (t6.1 and earlier
	not display it correctly, I hope that corrected at V6.1)

	<unit number>
	unit number available to you is range 0-1999 and they identified
	in a couple of group  in according to decram2.0 implementation
	to avoid confusion of operation.
	 o 0-999 for local node operation (it available on in the node).
	 o 1000-1999 for mscp served unit.

	<initialize volume>
	Using standard "initialize" dcl command with "/size=?" qualifier.
	for example;
	 $ initilize/size=16384/nohighwater/index=beginning fda0 volnam
	However, vms 5.5-2 and earlier running on your system, set volume
	size using provided utility FD$SETCHR before initialize it.
	for example;
	 $ mcr fd$setchr fda0/size=4096
	 $ initilize/nohighwater/index=beginning fda0 volnam

	<volume shadowing>
	Before mount fd psuedo disk unit as member of shadow set, you should 
	change device type. bellow is recommended operation sequence to
	mount shadow set  and restore after the unit unbound from shadow set.
	 $ mcr sysgen fda1000/noadapter
	 $ initilize/size=16384/nohighwater/index=beginning fda1000 volnam
	 $ mcr fd$setchr fda1000/shadow ! change device type to meet mscp server
	 $ mount/sys/noassist dsa1000/shadow=($1$fda1000,$3$fda1000) volnam
	   |
	 $ dismount dsa1000
	 $ mcr fd$setchr fda1000/noshadow ! restore device type
	 $!mount/over=(ident,shadow_membership) fda1000

	/shinozaki