Re: Unix File System vs. Raw Devices

>In Sybase on Unix, you always did all of your device/database creation on
>raw devices because the Unix FS buffers its writes thereby eliminating any
>guarantee that your log writes actually made it to disk. What's the story
>with Oracle 8 in this context? From the training that I've gone through
>for Oracle, everything seems to be so file/pathname oriented, that it
>doesn't seem like raw devices are even an option although I'm told they
>are.

I believe, that when Oracle background processes writes to files then it really writes. There's the flush function which empties FS buffers. That is in unix world. However, on NT filesystem (NTFS) it may not be true... In Oracle all caching is based on SGA shared memory. So there's no need to use FS caching anf flush function may be performed.

Using RAW devices gives you a bit better performance but if you want to run Oracle for example in archivelog mode, you'd better use filesystems.
Every restore/recovery method is much much easier when you use unix filesystem.

Regards,
Piotr
pkol_at_otago.gda.pl Received on Wed May 06 1998 - 01:49:56 CDT