This article hasn't been updated for over 5 years. The information below could be outdated.
SNDR (Remote Mirror) cheat sheet
Published Read time 1 min 48 sec(s) (2451 views).
Storage
Remote Mirror (SNDR/RDC), creates a network based mirror between two raw devices. When replicating, writes occur on the Primary Host's device no writes occur on the secondary host. When logging, writes may occur on either side, and are tracked through bitmaps.
Glossary
Word
Meaning
Primary Host
Contains primary device. All commands that manipulate the SNDR-set occur here after the set is enabled.
Secondary Host
Contains secondary device. The only command run here is the "enable" command, when the set is first created
Scoreboard
A bitmap. There is a bitmap for both primary and secondary devices. Bitmap becomes active when the SNDR-set goes into a "logging" state. Each bitmap tracks changes in the associated device when in "logging" mode.
SNDR comes up before DNS, NIS, and NIS+. The /etc/nssitch.conf should point to files for hosts and services. Only hosts that are in use by SNDR need be identified in the /etc/hosts table.
Useful commands
Command
Comments
/usr/opt/SUNWesm/sbin/sndradm
sndradm is equiivalent to rdcadm which is found in the same directory
/usr/opt/SUNWscm/sbin/dscfg
manipulates the data services configuration location
/usr/opt/SUNWesm/SUNWspsv/sbin/svadm
manipulates sv driver layer
/usr/opt/SUNWesm/sbin/sndrstat
shows statistics and state of SNDR-set
NOTE: All sndradm commands can be substituded for rdcadm commands for 2.x version of the software.