Обсуждение: HA for PostgreSQL (Auth-Server)

Hello *,

in my enterprise I have an Intranet-Server with NFSv4,  Courier,  Apache
and PostgreSQL and if this Server goes down, nothing will work anymore.

OK, I replicate the WHOLE server all 6 hours, but my PostgreSQL give  me
a bunch of headache, becasue I use "pam-pgsql" for authentication.

What is the best practize to build the PgSQL in HA using a  second/third
external server to keep authentication alive?

I am onging to put, the PostgregSQL on three or more Marvel MV78200 with
attached 4-port SAS controller (using three 74GByte SAS Drives in Raid-1
plus Hotfix) since the Intranet Database itself is only arround 13 GByte

Thanks, Greetings and nice Day/Evening
    Michelle Konzack

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On 24/06/10 17:27, Michelle Konzack wrote:

> in my enterprise I have an Intranet-Server with NFSv4,  Courier,  Apache
> and PostgreSQL and if this Server goes down, nothing will work anymore.
>
> OK, I replicate the WHOLE server all 6 hours, but my PostgreSQL give  me
> a bunch of headache, becasue I use "pam-pgsql" for authentication.

Honestly, using PostgreSQL for authentication in this environment may
not be optimal.

PostgreSQL is good at complex queries with a solid read/write mix, where
strong guarantees are required about concurrency, durability, etc. Its
strong point isn't in distributed read-mostly use serving huge numbers
of very simple queries.

You might be better off chosing an LDAP server. LDAP is designed for
extremely high rates of very simple queries - mostly single attribute
reads and simple tree searches. It's designed to operate as a
read-mostly system, where updates are infrequent. Most LDAP systems
provide very strong replication options, and most LDAP clients can use
multiple servers to service queries so they cope well when one of the
servers goes down.

> What is the best practize to build the PgSQL in HA using a  second/third
> external server to keep authentication alive?

Look into replication options like Bucardo and Slony-I. But, really,
you'll be much better off switching to using LDAP for this task.

OpenLDAP is a pretty solid LDAP server these days, and I highly
recommend it for use as an authentication database. By default it uses
Berkeley DB as a backend, which is quite acceptable with newer versions
of Berkeley DB that provide decent transactional behaviour and solid
crash-safety.

--
Craig Ringer

craig@postnewspapers.com.au (Craig Ringer) writes:
> OpenLDAP is a pretty solid LDAP server these days, and I highly
> recommend it for use as an authentication database. By default it uses
> Berkeley DB as a backend, which is quite acceptable with newer versions
> of Berkeley DB that provide decent transactional behaviour and solid
> crash-safety.

No disagreement there...

I wonder, with the recent interesting results from performance
comparisons between PostgreSQL and some of the key/value stores
(e.g. - where PostgreSQL has ways to "win"), what the performance
behaviour is, these days, for OpenLDAP backed by PostgreSQL.

It's not actually terribly difficult to set that up (as long as you're
not trying to use the "map some LDAP queries into relational ones"
functionality of slapd-sql, which makes me want to poke out my eyes).

At any rate, would be kinda cool to see numbers...
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