Re: Raw dev files

will@clsib21.clsi.us.geac.com (Will Roper) writes: >In article <38rriq$6j1@emory.mathcs.emory.edu> mikea@hpdmmfi.boi.hp.com (Mike Alder) writes: >>We have been bitten twice by some install programs this year that have >>gone through and changed the permissions on our informix raw dev files, >I have inserted lines in the boot files for all informix-using machines >to find the devices (we use a standard set of pathnames for links to them) >and set the permissions correctly. This has been working well for several >years now. An aside, on the issue of raw devices: it is very portable to create an 'aliased' device (ie., '/dev/rdb_root', '/dev/rdb_client'), which may allow access to whatever raw partition contains your data base data. Note that I said 'access' --- this should not be a hard link (for reasons you've brought to light here). This is of most use when you desire (or need) to avoid dbexport/dbimport or even more difficult manual methods (ie., sql :-) Examples? a) moving the data base to a new, compatible system, where the device names change (eg, from Motorola CISC to RISC, my own exerience). [[ We just set up analogous partitions on the new drives, used 'dd' to copy from one drive to the other (fast!), and used 'mknod' to put the cherry on top. ]] b) when hardware failures occur: ONCE UPON A TIME, there was a system with only one disk controller...until the controller died...then, the system acquirred 2 controllers, and all the SCSI device handles changed! This was before I started aliasing raw partition names... it was a kludgy fix, and involved moving the 'real' device handle to '/dev/{disk}.old', then having a 'dummy' handle with the same name in its place (but it really pointed elsewhere!). We never did have time to correct this before I left the firm...I wonder if anyone ever got to it? ;-) c) load balancing, the old-fashioned way ;-) When all you have to do to 'move' a partition is to 'dd' the raw partition(s), then remake the handles & restart the data base, life gets much easier... Note that I've applied this philosophy with other data bases (oracle, in b) above). It's a property/capability of UNIX, not data base technology... I'd be interested in hearing of others' experiences in this area; I'm not too old to learn a few new tricks (woof). -- William G. Hudacek Internet: whudace@andy.bgsu.edu 372-2911 (department) No Phone ;-( (office) University Computer Services (Hayes Hall, Rm 332) Bowling Green State University Bowling Green, OH 43403