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Home -> Community -> Usenet -> c.d.o.server -> Re: Unix File System vs. Raw Devices
A copy of this was sent to jgitomer_at_aol.com (Jgitomer)
(if that email address didn't require changing)
On 06 May 1998 03:16:20 GMT, you wrote:
>Hi Scott,
>
>One item in your post disturbed me.
> >
>>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.
>
>Oracle caches everything and only writes to disk when it is good and ready. If
>you ar running a production system be sure to have an adequate UPS for the
>server. If not, sooner or later, you will find yourself recovering from the
>last backup.
>
>Regards
>
>Jerry
>
>
>
>Jerry Gitomer Since I know how to spell DBA, I became one.
Oracle caches modified data blocks and uses DBWR to flush them in the background however, log file writes are not cached -- they are force written (fsync'ed) to the file system. DBWR and LGWR work together to ensure that sufficient data exists in either the datafiles on disk or the online redo log files to perform crash recovery.
A UPS is a good idea for many reasons but not needed to prevent data loss. The database takes care of that.
Thomas Kyte
tkyte_at_us.oracle.com
Oracle Government
Herndon VA
http://govt.us.oracle.com/ -- downloadable utilities
Anti-Anti Spam Msg: if you want an answer emailed to you, you have to make it easy to get email to you. Any bounced email will be treated the same way i treat SPAM-- I delete it. Received on Wed May 06 1998 - 09:43:24 CDT
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