Re: Practical maximums (was Re: PostgreSQL theoretical - Mailing list pgsql-general

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Scott Marlowe wrote:
> On Mon, 2006-08-07 at 14:51, Ron Johnson wrote:
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>> Scott Marlowe wrote:
>>> On Mon, 2006-08-07 at 13:51, Ron Johnson wrote:
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>>>> Jeff Davis wrote:
>>>>> On Mon, 2006-07-31 at 09:53 -0500, Ron Johnson wrote:
>>>>> pg_dump just produces output. You could pretty easily stripe that output
>>>>> across multiple devices just by using some scripts. Just make sure to
>>>>> write a script that can reconstruct the data again when you need to
>>>>> restore.
>>>> But doesn't that mean that pg_dump must dump to disk?
>>>>
>>>> With a *big* database, that's a whole lot of extra kit (not just
>>>> spindles) to buy.
>>> I'm certain you can backup direct to tape, as I've done it in the past
>>> with postgresql.  This was in the day of 4 gig 4 mm tape drives...
>> Sure.  That's why tar is named *Tape* ARchive.
>>
>> Going along with the example of the 4GB 4mm tape drive, and to
>> simplify, we are *not* using compression (neither on the drive or
>> s/w gzip or bzip):
>>
>> Say we have a 7GB database.  Is there a way to way to use 2 tape
>> drives...  Argh, I guess not, since the Unix pipe mentality presumes
>> that the mode of operation will be:
>>   $ pg_dump /some/database | tar cvfz /dev/st0/db.tgz
>>
>> What would be darned useful (but only, I think, with heavy usage of
>> tablespaces) is:
>>   $ pg_tapedump /some/database /dev/st0,/dev/st1,/dev/st2,/dev/st3
>
> Oh, I see where you were headed.
>
> I've found a bit here and there googling about for multiplex and tar,
> and found an IO:Multiplex module for perl.
>
> I don't see why someone couldn't make use of it to create some kind of
> system where you'd do:
>
> pg_dump dbname | perl mulitiplexscript device1,device2,device3,devicen
>
> No need for postgresql to support it directly.  Restoring would likewise
> just be a reverse operation.

Interesting.  Many thanks.  Scary though that it hasn't been touched
in 30 months.

With multiple SCSI cards, each with it's own tape drive, this
immensely speeds up the backup operation.

- --
Ron Johnson, Jr.
Jefferson LA  USA

Is "common sense" really valid?
For example, it is "common sense" to white-power racists that
whites are superior to blacks, and that those with brown skins
are mud people.
However, that "common sense" is obviously wrong.
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