Re: Row Devices and Chunk offset

In article <344CE734.46A7@bloomberg.com>, "Art S. Kagel" <kagel@bloomberg.com> writes >Omni Hotels Reservation Center wrote: >> >> Phillipe, >> I can confirm this. We run AIX and when we initially set up we had to use >> the same offset. The information came from the Informix engineer who >> helped us configure. However, I have not seen documentation to back up >> what she said. Since the configuration has never caused a problem, I have >> always used the offset since. >> Dave Thacker >> Omni Hotels Reservation Center >> >> Philippe Meylan <Meylan@steria.ch> wrote in article >> <622h0a$1sa@cssun.mathcs.emory.edu>... >> > We are using INFORMIX 7.1x and our chunks are located on row devices. IBM >> >> > inform us that an offset of 512 bytes is required between the base of the >> >> > row device and the beginning of the chunk. This area should be used by >> AIX >> > for system management. >> > >> > My question : >> > >> > This requirement is undocumented and the ONINIT tools doesn't reserve any >> >> > offset when creating a new chunk. It's this requirement justified and can >> >> > be applied on any platform ? Has Informix a document explaining that > >The requirement is sstem dependent and actually probably unneccessary >unless the device is also being used for filesystems at other offsets or >is part of a software stripe set. Other OS's make similar requirements, >on Ultrix it was the last 2K of the drive/device unless the drive was on >a stripe set then the first 2K was also forbidden. Informix cannot >keep track of all of the vendors' various ideosycroses (SP?). > >Art S. Kagel Solaris 2.5.1 it is the first 8K EVEN IF IT IS ONLY BEING USED AS A RAW DEVICE. The VTOC on the front MUST be valid or else Solaris 2.5.1 CANNOT access it at all! Solaris 2.4 it was the first 4K of the drive so the required value can change with not just the OS but also the RELEASE of the OS. -- David Williams