Re: The 2GB chunk size limit and Sparc storage arrays

Mike Reed - Radiix <mreed> wrote: >Does anyone know if Informix will be removing the 2GB >chunk size limit anytime soon? <STUFF SNIPPED> >names). If this is true, then I can only have 42 - 2GB Mike I assume your SUN rep. was not referring to an Informix limitation. You did not mention which version you are using but with version 5 there was a problem which limited the number of chunks which could be created in a single instance. This was due to the way chunks were tracked. The chunks were tracked via a SINGLE reserved page, thus you could only have as many chunk path names as you could fit on a single page. To calculate the limitation: take the page size, deduct 28bytes for the page header, then deduct around 29bytes (per chunk) plus the length of each pathname. With a 2K page system and pathnames of around 12bytes the limitation would be roughly the same as what you have quoted - 45 chunks per system (each being a maximum of 2GB). In version 6 and above the single reserved page limit was lifted (and is now unlimited I believe). One way to get as much disk space as possible in version 5 is to make all the chunk path names very small (eg /i/c1...) and then link the chunk to the real device (eg /dev/chunk1 ...). There was also a limitation on the number of dbspaces - in ver 5 this was around 38 (for a 2K page system) - it is now 2,047 in version 7. Regarding the 2GB limit per chunk- in version 5 this was due to an internal limitation which meant that only 1,048,576 pages could be referenced for a single chunk. However the 2GB limitation was affective even with a 4K page size! I believe this limitation still exists in ver 7.11, however with an unlimited number of chunks this should not be a problem any more. +--------------------------------------------------------+ | Gavin Nour: nourg@acslink.net.au | | Director: Select Software Solutions Pty Ltd. | | Secretary: Informix User Group NSW, Australia. | | Committee member: International Informix User Group. | | Mobile: +(61) 0419 803 113 | +--------------------------------------------------------+