Re: PANIC-crashes with INFORMIX-ONLINE

In article <5di3gj$12h@boell.softcon.de>, Matthias Apitz <guru@SoftcoN.de> writes > >I'm posting this in behalf of one of our partners. Please reply to >me (matthias.apitz@softcon.de) and Schneider@HRZ.Uni-Dortmund.De. >Thx in advance. > > matthias >-- >We observed several PANIC-crashes with INFORMIX-ONLINE >Version 7.12C1X2 on SNI's Reliant UNIX 5.43. > >The error messages and the restart protocol (in online.log) >were like this: > >21:32:42 Checkpoint Completed: duration was 0 seconds. >21:38:51 Pool = 0x2267e010, Pool name = 12, Blkhdr = 0x22682bdc >21:38:51 Block magic is 24, expecting 24 >21:38:51 Possible memory block trailer corruption >21:38:51 mtshpool.c, line 2549, thread 36, proc id 16201, > Condition Failed (CHECK_ALLOC_BLOCK), In (mt_shm_free) > Thread(36, sqlexec, 0, 3). >21:38:51 PANIC: Attempting to bring system down> Looks like a bug to me. Either that or 2 areas of swap space are configured to overlap (I've heard of that happening before). Check nothing overlaps swap space on the machine (another swap area or even a filesystem). If not then it is a bug. >Thu Feb 6 21:39:23 1997 > >21:39:23 DR: DRAUTO is 0 (Off) >21:39:24 INFORMIX-OnLine Initialized -- Shared Memory Initialized. >21:39:24 Physical Recovery Started. >21:39:24 Physical Recovery Complete: 0 Pages Restored. >21:39:24 Logical Recovery Started. >21:39:27 Logical Recovery Complete.> 0 Committed, 0 Rolled Back, 0 Open, 0 Bad Locks > >21:39:27 Dataskip is now OFF for all dbspaces >21:39:27 On-Line Mode >21:39:27 Checkpoint Completed: duration was 0 seconds.> >Up to now in all cases the both values "Black magic" >and "expecting" were absolutely identical (here = 24). > >The following script served as a "reliable crash-trigger": > > select d02bnr, d02bg from d02ben where d02bnr < 19960000 ;> >I started the script in the dbaccess-dialog-environment >and the command "isql - crashtest" in a ksh, >both with the same result. > >To produce a crash, I had to start this select-command twice. >The first run is ok. But starting it again immediately after >finishing the first run - to display the first hits again - >results in a crash. >The script behaved this way on two different databases >(in different dbspaces) with absolutely different data >(but the same table-structure). > >I varied the script and the data and found, that with a reduced >comparing limit (199600) the very same script runs absolutely save. >But increasing to 1996000 results in a crash as well. The variable >d02bnr is defined as varchar(12,0), but it is filled only with pure >numbers (fixed-length strings with leading zeros). SQL does an >"implicit type conversion" to compare the string with the integer. > >When I used a string instead, INFORMIX didn't crash. >This was save: > > select d02bnr, d02bg from d02ben where d02bnr < "19960000" ;> >I created a new table - a twin in the same dbspace with identical >structure but slightly different names for key-variables and indexes. >The table was filled with the same data, but INFORMIX didn't crash - >under no circumstances. > >I played the game with >INFORMIX-ONLINE V7.12.UC1X2, >Reliant UNIX 5.43 B0045, >RM600 3/640 R4000 (SNI-mips-machine). > >Any ideas? > >Feb 7 1997 >Schneider@HRZ.Uni-Dortmund.De -- David Williams