vgchange -c y -S y /dev/vgname...

[Dan Copeland]

Admins,

I'm not sure why this practice was started, but whenever we create a volume group for use in a package, we always mark it as sharable as well as setting the cluster bit. We are not sharing the volume group across multiple nodes and never have. Can someone shed some light as to why we do this. Is this standard practice for older versions of MC/SG? The senior members of my team don't know why they started doing it this way either...

tia,
Frank

[Robert Gamble]

Frank,

Takr a look at the following items:

Doc ID A5004085 http://www1.itrc.hp.com/service/cki/docDisplay.do?docLocale=en_US&docId=200000062945536

http://docs.hp.com/cgi-bin/fsearch/framedisplay?top=/hpux/onlinedocs/B3921-90010/B3921-90010_top.html&con=/hpux/onlinedocs/B3921-90010/00/08/848-con.html&toc=/hpux/onlinedocs/B3921-90010/00/08/848-toc.html&searchterms=y%7cy%7cvgchange&queryid=20030218-072826

Good Luck!

[melvyn burnard]

No htis is not standard practice.
The VG's get marked as cluster aware at time of applying the cluster binary. the only reason to redo a vgchange -c y is when you have marked the vg cluster unaware, or have redone a binary apply without hte vg activated at the time.
The practic may have begun because someone just wanted to make 110% sure.

[John Poff · Accepted solution]

Hi Frank,

I don't know of any reason for marking the VGs as shareable if you aren't mounting them that way. The only reason for a VG to be shareable is if the VG is going to be available for read/write on multiple nodes at the same time, which is a pretty wild situation. Normally a VG in MC/SG gets activated in exclusive mode, which prevents any other node from accidentally activating the VG while in use by another node. Marking all the VGs as shareable may be bypassing that safeguard.

Good for you for asking the question at your place! Sometimes things get done 'just because we've always done it that way', and it's wrong. You must be related to the boy who questioned the emperors' new clothes. :)

JP

[Artyom Voronchihin]

Hello !
You dosn't need -S option if you are not going to share VG across multiple nodes. Shared access to VG is designed to be used only by specialized distributed applications that use raw access to disk, rather that going through a file system. The applications must provide their own concurrency control for their data, as well as transaction logging and recovery facilities.