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Re: The limit of the unlimited ?

From: Howard J. Rogers <howardjr2000_at_yahoo.com.au>
Date: Sun, 08 Sep 2002 08:36:37 +1000
Message-ID: <3d7a7f35@dnews.tpgi.com.au>

Roye Avidor wrote:

> So, if I have a 200G filesystem and in the future it will expand
> I wont have the option to use the whole filesystem ? unless i will
> create more datafiles to the tablespace ? ( and this last can only
> happen manualy ). ?


Correct, and it would be utter madness to want datafiles of such a large size anyway, even if you were allowed them by your filesystem and/or koert's mathematics.

Large files means large backups (it's all or nothing at backup time, so if you have 1 16Gb file, and I have 8 2Gb files, you must back up all 16Gb, whereas I can get choosey and backup 1 2Gb file each night for a week and a bit).

Large files also mean large non-availability issues. When your 16Gb file gets corrupted, the entire 16Gb is off air until you fix it. When one of my 2Gb files goes wonky, I have 14Gb of data still usable and available whilst I'm performing my (much smaller/quicker) recovery.

Oracle allows you to have 1022 datafiles per tablespace: take advantage of their generosity.

Incidentally: it doesn't have to be a manual exercise to add the other files in. Enterprise Manager has a nifty set of alerts ("Events"), one of which is 'tablespace more than x% full'... and if triggered, you can get EM to carry out a "fixit job" ...which in this case would be 'add a new datafile'. And I dare say that shell scripters anonymous would have (or be able to develop) something very similar for the command-line buff.

Regards
HJR

> 
> 
>> 
>> In article <tvoe9.106911$8o4.14887_at_afrodite.telenet-ops.be>, koert54
>> wrote:
>>>>> max of 2^10 datablocks = 4194304
>>> should be 2^22
>>> 
>>> "koert54" <nospam_at_spam.com> wrote in message
>>> news:xuoe9.106909$8o4.14886_at_afrodite.telenet-ops.be...

>>>> The maxsize of a datafile is limited by the structure of the DBA
 (datablock
>>>> address)
>>>> and the blocksize (unless ulimit is hit first)
>>>> Typically :
>>>> - the dba is 4 bytes
>>>> - 10 bits represent the filenumber (oracle/platform specific)
>>>> - that leaves 22 bits for the blocknumber
>>>> thus a datafile can have a max of 2^10 datablocks = 4194304
>>>>

>>>> So blocksize of
>>>> 2K -> max of 8GB
>>>> 4K -> 16GB
>>>> 8K -> 32GB
>>>> 16K -> 64GB
>>>>
>>>>

>>>> "Roye Avidor" <att_at_internetdollar.com> wrote in message
>>>> news:slrnank3hn.dt4.roya_at_www.attbi.com...
>>>> > Hi all,
>>>> > I installed Oracle 9.2.0 on linux ( RedHat7.3).
>>>> > This release of linux can create very big files.
>>>> > When I'm create a tablespace an sets the maxsize
>>>> > to unlimited, I'm getting in the dba_data_files
>>>> > a maxsize of 16G.
>>>> >
>>>> > Is this the limit that 9.2.0 can handle ?
>>>> >
>>>> >
>>>> > Thx,
>>>> > Roye Avidor
>>>> >
>>>> >
>>>>
>>>>
>>> 
>>>
 
Received on Sat Sep 07 2002 - 17:36:37 CDT

Original text of this message

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