05-May-2007

Sneaky performance tricks

Want the read performance benefits of a RAM disk with physical disk protection? Don't want to spend money? Try this nice little trick (on Alpha/IA64 8.2 and later with volume shadowing and LDDRIVER installed):


$ mc mdmanager
DECRAM> create disk mda1:/capacity=2000/persist/alloc=1
DECRAM> ^Z
$ init/sys $1$mda1: ramdisk
$ create/directory sys$sysdevice:[ld]
$ ld create/size=2000 sys$sysdevice:[ld]shadow_mda1.dsk
$ ld connect sys$sysdevice:[ld]shadow_mda1.dsk lda1:
$ init/sys $1$lda1: ramdisk
$ mount/system dsa1:/shadow=($1$lda1:,$1$mda1:) ramdisk ramdisk

The shadowing driver is smart enough to perform all reads from the RAM disk.

Posted at May 5, 2007 1:41 PM
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Comments

but doesn't this need a DECRAM licence as well as a SHAD0Wing licence ?

Posted by: Ian Miller at May 6, 2007 2:34 AM

DECRam is integrated into the operating system as of version 8.2.

Posted by: Jim Duff at May 6, 2007 12:02 PM

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