| From: | John R Pierce <pierce(at)hogranch(dot)com> |
|---|---|
| To: | pgsql-general(at)postgresql(dot)org |
| Subject: | Re: question about readonly instances |
| Date: | 2011-05-19 07:05:17 |
| Message-ID: | 4DD4C12D.3040105@hogranch.com |
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| Lists: | pgsql-general |
On 05/18/11 11:39 PM, Szymon Guz wrote:
>
> thanks for the answer. It is not a problem to have 3 oracle instances,
> in fact there will be hundreds of them probably, but could also be
> hundreds of Postgres instances :)
do you have any idea how EXPENSIVE 100s of Oracle RAC nodes are annually?
to share block storage between cluster nodes requires a cluster-aware
file system, as conventional file systems do not expect the disk files
to change behind their back. these cluster-aware file systems have
a bunch of overhead in maintaining cache coherency between nodes, and such.
as far as I know, postgres can not be run on a read only file system,
further its shared_buffer caches couldn't possibly be aware of other
nodes modifying blocks that happen to be cached.
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