Re: Informix 2.10 Splitting Data Across File Systems?

->Subject: Re: Informix 2.10 Splitting Data Across File Systems? ->Date: Thu, 29 Sep 1994 13:13:46 GMT ->Reply-To: jh@cadre.com (Joe Hartley) ->Organization: Cadre Technologies Inc. -> ->We know now that there are two ways to split a DB across file systems. ->It seems to me that Jon's approach is easier from an implementation ->point of view than Alan's. Are there any drawbacks to either method? ->does the symbolic link pose any hits on performance? It seems that ->the 2 different approaces would work equally well. Any disagreements? -> ->========================================================================== -> Joe Hartley - jh@cadre.com - Cadre Technologies, Inc. I am beginning to believe that Jonathan Lefler's approach to splitting SE databases across file systems by using symbolic links is actually superior to my suggestion of putting hard pathing into the system catalog in column "systables.dirpath". Working at this level, one is obviously concerned with the files in which Informix stores the data tables. Thus there is some small advantage in having *every* file for a database show up in the "dbname.dbs" directory, even if some of those files are actually symbolic links. I have temporarily "lost" files, until I looked in the dirpath to see where they were located. However, it seems to me that the main advantage of using symbolic links is that it enables one to separate index files from data files, placing them on separate devices. (Separating *.dat and *.idx is not possible with the dirpath method.) This separation can result in reduced disk read head contention when doing bulk reads from a table in index order. The benefit of this is reduced as more users access the disks, since other users' requests will probably move the read heads away from the data and index files. However, batch updates and/or reports which are often run at night when few other users are logged in will benefit. This may allow a moderate to large database, sitting in the overlap zone between SE and OnLine size ranges, to continue as SE and avoid or postpone the difficulties of migrating from SE to OnLine. Regards, Alan ___________________________ ______________________| R. Alan Popiel |__________________________ \\ Internet: | Martin Marietta, SLS | / \\ alan@den.mmc.com | P.O. Box 179, M/S 3810 | Std disclaimers apply. / )Voice: | Denver, CO 80201-0179 USA | ( / 303-977-9998 |___________________________| (But you knew that!) \\ /________________________) (____________________________\\