Re: raw devices - general questions

Allen Jantzen wrote: > > I have 2 4-gig SCSI drives (one for a primary, one for a mirror) that > I want to configure as raw devices for Informix 7.13UC1 - a data > warehouse. > > A few questions: (please forgive if they are of a newbie nature) > > what exactly is the offset that informix is asking for when I create > my dbspace and initial chunk? Is it in tracks? Is it the number of > tracks to skip before writing data OR the track number to start > writing at??? > I think the SCSI drive has a table of contents/VTOC at track 1, which > I obviously want to leave alone. Would my offset be 1 or 2?? > > I was hoping to create two 2-gig chunks on the drive. Because > Informix has a 2-gig chunk limit, does this mean that it can't access > or "go past" the first chunk on the drive??? Will my second chunk be > available? If so, how do I calculate the offset for the 2nd chunk?? The offset is specified in Kbytes. If one track is used by the controller then specify the offset as the size in K of one track. Make this value larger, rather than smaller. The 2 Gbyte size limit is per chunk. You can assign as many chunks to a dbspace as you want. You can also define as many chunks on the same disk as you want, providing the offset is set correctly. There was a bug in 5.something where the offset PLUS the size could not exceed 2 Gbytes. But I am sure this is fixed in 7.13. ;-) If you don't want to calculate offset values every time, then just create partitions under the OS, and use those. Just remember to create links to the physical devices and use the link names in your configuration. Hope that helps, -- Mark. +-------------------------------------------------------------------------+ |Mark D. Stock - The West Solutions Group http://www.west.co.za | | The Informix FAQ is at http://www.iiug.org | |mailto:marks@west.co.za +------------------------------------------------+ |Tel: +27 11 803 2151 |If it doesn't work... force it! | |Fax: +27 11 803 2189 |If it breaks... it needed replacing anyway! | |Cell: +27 83 250 2325 |Well, that's how I code anyway! | +------------------------+------------------------------------------------+