[Postgres-xl-developers] Backup and recovery

Joakim Lundgren lundgren700 at gmail.com
Mon Aug 17 00:48:00 PDT 2015

Hi again Pavan!

I have one more question related to backup and recovery.

It appears to me that pg_basebackup copies the "coord" directory only, but
not the "dn_master" directory. Is that right?

I assume that the data should be in dn_master and not coord. Can you
perhaps clarify this to me?

/Regards Joakim Lundgren

2015-08-14 10:02 GMT+02:00 Joakim Lundgren <lundgren700 at gmail.com>:

> Thanks Pavan!
> If I understand correctly, creating a barrier is only needed if you want
> to recover to a specific PITR, set by the given *barrier_name, *but it
> secures that any cluster wide transactions will be consistent when
> recovering. If a barrier is not created, recovery is done until the time
> when the database crashed, which is what I want to achive, but in that case
> cluster wide transactions may be inconsistent. Do I get that right?
> If my understanding is right then, there is no secure way to recover until
> "crash time" knowing that no transaction will be inconsistent? How should
> one do to achive recovery "almost to the time" when the database crashes?
> Is that to set barriers regularly and live with the facy that some
> transactions might be lost?
> /Regards Joakim
> 2015-08-13 15:53 GMT+02:00 Pavan Deolasee <pavan.deolasee at gmail.com>:
>> On Tue, Aug 11, 2015 at 2:17 PM, Joakim Lundgren <lundgren700 at gmail.com>
>> wrote:
>>> Hi!
>>> I'm struggling some with backup and recovery of a postgres-XL cluster
>>> over several nodes. I have read the manual and are using pg_basebackup to
>>> do a hot backup.
>>> My question is if there are any best practices how to do a full backup
>>> and recovery of a cluster. Do I need to pg_basesetup on each node storing
>>> data or is there any script that do the full backup on each node?
>> Yes, you need to backup each node individually. There had been some
>> discussion about either extending pgxc_ctl or extending one of the other
>> backup/recovery utility to do cluster wide backup. But AFAIK there is
>> nothing in place yet.
>>> If you run pg_basesetup on each node, do they have to be synchronized in
>>> some way.
>> There is a concept of BARRIER which can be used to create cluster-wide
>> point to which each component can recovery and guarantee global consistency.
>> Barriers can then be used in recovery.conf.  Each node is supposed to
>> recover to the same barrier. Also please keep in mind that the cluster does
>> not provide any mechanism to guarantee uniqueness of barrier names. Hope
>> this helps.
>> Thanks,
>> Pavan
>> --
>>  Pavan Deolasee                   http://www.2ndQuadrant.com/
>>  PostgreSQL Development, 24x7 Support, Training & Services
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