Re: RAM disk usage

From: Norman Soley <soley_at_trooa.enet.dec.com>
Date: 24 Jun 92 21:44:40 GMT
Message-ID: <1992Jun24.210537.11090_at_engage.pko.dec.com>


In article <92174.164842KML110_at_psuvm.psu.edu>, <KML110_at_psuvm.psu.edu> writes...
>Is anybody out there using a RAM disk as part of their database? I'd be
>interested in hearing about good/bad experiences, what tablespaces or files
>are on the disk, what happens during system crash, recovery procedures, and
>what sort of differences it really made to your system usage.

I have used a ram disk to hold .frm files and such on occasion this does improve form load time, which can be a big deal for some situations.

Oracle updates the control block in every data file when it starts up, if the system crashes that update is lost. Keeping a reference file on hard disk and copying it over to the RAMdisk doesn't work because Oracle now thinks this is an old file and tells you it needs to be recovered. One could theoretically cobble up a scheme where the file on the ramdisk was recreated from scratch each time the database is brought up.

If you've got extra RAM lying about why not just bump up the block cache in the SGA. Should have pretty much the same effect.

Now if you were talking about a solid-state disk like the DEC ESE50 (i.e. non-volatile) that would be a different story.

--
    Norman Soley, Specialist, Professional Software Services, ITC District
    Digital Equipment of Canada                   soley_at_trooa.enet.dec.com
    Opinions expressed are mine alone  and do not reflect those of Digital 
    Equipment Corporation or my cat Marge.
Received on Wed Jun 24 1992 - 23:44:40 CEST

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