Re: Can data pages in IDS act like a torn page in SQL ser

----- Original Message ----- From: R.... Konikoff <konikoffr@BRAGG.ARMY.MIL> At: 5/19 15:32 > Me: INFORMIX-OnLine Version 7.23.UC11 > > OS: HP-UX 11 > > One of our MS-SQL server guys came over and explained that he experiences > "torn pages" where a corrupt data element leaves a partially filled page and > skips to another page. All of his stuff lives in the lofty towers of cooked > space. As such, he indicated a steep overhead price for self maintenance > and space recovery. > > I'm a functional analyst, not the DBA, so I'm not even sure if I'm asking > this right, but here goes: > > Since INFORMIX manages the disk space directly (forever raw!), if we only > have a partial page fill and it skips to the next extent, shouldn't INFORMIX > reclaim that space with the integrity checks and whatnot? I do not understand the question. If a data page is physically corrupt, then the chunk that it belongs to, and that chunk's dbspace, will be marked 'OFFLINE' and will be inaccessible until restored from an archive. What do you mean by 'skips to the next extent'? IDS will insert new rows by first looking for a partially used page to 'home' the row if a row is smaller than a page. If there are no partially used pages, or the row is larger than a page, an unused page from an existing extent is selected as the row's home page. If there are no free pages in existing extents a new extent is allocated from the unused space in chunks belonging to the dbspace housing the table or fragment. Integrity checks? You do not mean relational integrity checks, you are referring to the page consistency checks? As I stated above, if a page fails a consistency check the chunks and dbspace will be marked down and have to be restored from an archive. Art S. Kagel