Re: adding raw space

Michael L. Gallagher wrote: > > I have been trying to add raw space to my server for some time now. I can add cooked files until > the sun sets. The device I'm trying to use is /dev/rdsk/c0t3d0s0 and its vtoc looks like this: > > * /dev/rdsk/c0t3d0s0 partition map > * > * Dimensions: > * 512 bytes/sector > * 72 sectors/track > * 14 tracks/cylinder > * 1008 sectors/cylinder > * 2038 cylinders > * 2036 accessible cylinders > * > * Flags: > * 1: unmountable > * 10: read-only > * > * First Sector Last > * Partition Tag Flags Sector Count Sector Mount Directory > 2 5 01 0 2052288 2052287 > 7 0 00 0 2052288 2052287 > > This is a 1 Gig disk that I would like to have half primary and half mirror (I know this may be a > bad design for performance, but I'll change it once I learn more). I tried calculating an offset of > 32688K or something like that based on the above information. What is the correct offset? I have > all links owned and grouped to informix, so I know that's not a problem. Thanks for the help. First of all, it's not just bad performance to split a single disk up half primary and half mirror, it completely defeats the object. You mirror a chunk to protect it against hardware failure - typically disk or controller. Since, by definition, what you're trying to do is to use both the same disk and controller, it's completely futile. Secondly, most operating systems keep the VTOC on the first cylinder of a disk, so you should avoid using this first cylinder in a raw device. To answer your question, if you really want to go ahead, and you're sure you have a 1GByte disk, the correct offset is 0 for the first chunk, and 500,000 for the second. Neil Truby Chase Manhattan Bournemouth, UK