Re: Incremental Archive performance issue......

"Five Cats" <cats_spam@[127.0.0.1]> wrote in message news:OhnEx9ADObfAFwwd@[127.0.0.1]... > In message <c5ju7r$2jjcs$1@ID-162943.news.uni-berlin.de>, Neil Truby > <neil.truby@ardenta.com> writes > >"Five Cats" <cats_spam@[127.0.0.1]> wrote in message > >news:Hc7W+WA3NmeAFwKT@[127.0.0.1]... > >> In message <c56p0h$cfc$1@terabinaries.xmission.com>, Alexey Sonkin > >> <alexeis@grandvirtual.com> writes > >> > > > > >> >For L1 archive, the backup speed is mostly limited by the > >> >disk array throughput: as I've already mentioned, Informix > >> >must read the entire database (like in L0 archive) > >> > >> Surely this depends on some extent as to how much of the database has > >> actually changed since the last L0 archive? > > > >And how, pray, is the Informix engine to know if a page has changed since > >the last level 0 archive???? > > The date stamp on the page. OK, but it has to read the page to know this. So Informix has to read all pages (at least, all those with at least some data in them), even for an incremental backup.

Neil Truby wrote: > > "Five Cats" <cats_spam@[127.0.0.1]> wrote in message > news:OhnEx9ADObfAFwwd@[127.0.0.1]... > > In message <c5ju7r$2jjcs$1@ID-162943.news.uni-berlin.de>, Neil Truby > > <neil.truby@ardenta.com> writes > > >"Five Cats" <cats_spam@[127.0.0.1]> wrote in message > > >news:Hc7W+WA3NmeAFwKT@[127.0.0.1]... > > >> In message <c56p0h$cfc$1@terabinaries.xmission.com>, Alexey Sonkin > > >> <alexeis@grandvirtual.com> writes > > >> > > > > > > >> >For L1 archive, the backup speed is mostly limited by the > > >> >disk array throughput: as I've already mentioned, Informix > > >> >must read the entire database (like in L0 archive) > > >> > > >> Surely this depends on some extent as to how much of the database has > > >> actually changed since the last L0 archive? > > > > > >And how, pray, is the Informix engine to know if a page has changed since > > >the last level 0 archive???? > > > > The date stamp on the page. > > OK, but it has to read the page to know this. So Informix has to read all > pages (at least, all those with at least some data in them), even for an > incremental backup. exactly this! The engine must read all pages (even those, which have no more any data in them - as this might be the change), but Level 1 in contrary to a full system backup (Level 0) in general terms brings less pages onto the XBSA pipe or onto the respective SW interface of ontape, and therefore is rather less dependant on the tape speed (or output speed to disk if using disk pools or ontaping to disk) And YES - as J. Tong pointed out many times: ontape to disk never was unsupported! :)))) dic_k -- Richard Kofler SOLID STATE EDV Dienstleistungen GmbH Vienna/Austria/Europe