Re: How to compile with different MAXALIGN?

From: Sean Murphy <Sean(dot)Murphy(at)equipoint(dot)com>
To: pgsql-admin(at)postgresql(dot)org
Subject: Re: How to compile with different MAXALIGN?
Date: 2007-04-04 22:26:45
Message-ID: 46142625.9060204@equipoint.com
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Actually the colo machine is running Windows as well (not my call, but
there are other workloads on it) but Ubuntu is running under VMWare, so
I could install a truly identical copy of the colo "machine" on the same
server I'm moving from...

Thanks!

Andy Shellam wrote:
> Is there any chance of you setting up a temporary machine on the same
> network as your Windows one but an identical build as your co-located
> machine? Then you can transfer your Windows data to Linux using
> pg_dump/restore, switch your apps over to the Linux machine, then use
> WAL files to mimic the changes onto your co-location.
>
> Once you're new co-lo machine is at the same stage as your temporary
> one, switch the application over to your co-lo machine and turn the temp
> and Windows machines off.
>
> Failing that perhaps someone with experience of Slony would be able
> guide you if this is possible with Slony?
>
> Andy.
>
> Sean Murphy wrote:
>> We're talking about 12 GB of data... to do the [probably ill-fated]
>> binary copy in any reasonable amount of time required a portable hard
>> drive and sneaker-net...
>>
>> That's why I'm anxious, probably to the point of stupidity, to avoid a
>> situation where I'll have to bring the db down long enough to pull a
>> backup dump onto portable media, drive to the colo, and restore it...
>>
>> (I'll do a pre-live test run of whatever procedure I go with, but...)
>>
>> Sean
>>
>> Andy Shellam wrote:
>>
>>> From experience I would say NEVER NEVER try and do a direct copy across
>>> different platforms (Windows -> Linux.)
>>> Someone may contradict me, but I think a dump/restore would be the way
>>> to go.
>>>
>>> What sort of size of data are we talking? You'll need to factor in the
>>> time it takes to dump the data, the time it takes to transfer the dump
>>> to your new machine, and the time it takes to restore it.
>>>
>>> Andy.
>>>
>>> Sean Murphy wrote:
>>>
>>>> I'm in the process of moving a large database from an in-house Win32
>>>> server to a co-located Ubuntu Linux server. The data's in constant use,
>>>> so I can't really bring the server down for more than a half hour or
>>>> so,
>>>> and I'd like to go ahead and use a base backup + WAL restore
>>>> strategy to
>>>> sync the servers up before flipping the switch.
>>>>
>>>> After copying over my base backup and setting ACL appropriately, when I
>>>> go to start the server on Linux it fails with a message in the log
>>>> stating that the cluster (binary copy from the W32 server) is
>>>> initialized MAXALIGN 8 and the server is compiled MAXALIGN 4. A search
>>>> of the Docs tells me that I can compile the server with a different
>>>> MAXALIGN, but the install docs don't give any indication how this is
>>>> achieved. Is there a configure or gmake option I can feed, or do I need
>>>> to change a line in one (or more) of the source files?
>>>>
>>>> Or is there a compelling reason (I'm absolutely ignorant here) to do a
>>>> dump and restore instead of the binary copy because MAXALIGN 4 is
>>>> better
>>>> for performance/security/fill-in-the-blank?
>>>>
>>>> Or is a binary copy move from W to L hopeless even if this particular
>>>> issue isn't?
>>>>
>>>> Thanks
>>>> Sean
>>>>
>>>> ---------------------------(end of
>>>> broadcast)---------------------------
>>>> TIP 3: Have you checked our extensive FAQ?
>>>>
>>>> http://www.postgresql.org/docs/faq
>>>>
>>>>
>>>>
>>>>
>>>>
>>>
>>
>>
>> ---------------------------(end of broadcast)---------------------------
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>>
>>
>>
>
>

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