Re: Using SAN Splits to instantly copy a DB

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On 11/15/06 15:51, Martijn van Oosterhout wrote:
> On Wed, Nov 15, 2006 at 03:25:38PM -0600, Ron Johnson wrote:
>> However, what if the WAL is not on the SAN? You'd have to shut down
>> pg anyway, in order to copy the WAL to a new directory, no?
>
> You have to copy the *entire* cluster, you cannot split out one
> database, for example. Two postmaster instances cannot share data,
> period.
>
>> Lastly: in order to do SAN splitting without risking your data,
>> wouldn't you have to configure the disks as RAID-15 (mirrored
>> RAID-5), since splitting a RAID10 would leave you with stripesets?
>
> As long as you get all the data it OK. I'm not 100% clear on what SAN
> splitting is so I'm not totally sure.

If it's anything like what happens on SCSI controllers, you can
break a mirrorset and wind up with 2 identical JBODs. Similarly,
you can break a RAID-10 set into 2 identical RAID-0 sets.

- --
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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