Re: performance of rootdbs in non-raw file

In article <33B5E852.656C@echonyc.com>, Cosmo Lee <cosmo@echonyc.com> writes >I have a client who created their rootdbs in a Unix file instead of a >raw device. I'm wondering what kind of hit this is going to be >performance-wise. > As Madison says, rootdbs should be on a raw device. >The rootdbs only contains whatever system files Online created there - >no user databases are there. > >Is it worth it to move the file to a raw device or is all the >administrative info stored in there pretty much read into memory when >Online starts up (the DB doesn't have many tables)??? > Is is read in but there are a lot of writes as the reserved pages in the root dbs get updated every time a checkpoint occurs. Remember the two checkpoint reserved pages (PAGE_1CKPT and PAGE_2CKPT)? They also contain logical log information (Log file flags, Timestamp when log filled, date and time the log filled) which must get updated regularly... [Also the two archive reserved pages get updated eery time an archive is done.] Mainly the load comes from checkpoints and logical logs changing status (filled,written to tape etc). You would be surprised how many writes go to the rootdbs even when logical/physical log files have been moved elsewhere.. >My guess would be that this administrative info wouldn't have to be >accessed too frequently, since most action is seen on actual data >chunks. But this guess conflicts with the recommendations of moving the >Physical and Logical log files to dbspaces other than the rootdbs - why >is that?? > >Thanks. -- David Williams