Re: Portworx snapshots

Stephen,

Our application don't write lot of data, so i don't think the time taken on
replaying the WAL will be an issue for us.

For reliability, as you said, i was thinking in running a large pgbench
which writes a lot of data, while taking snapshots.
Then my idea was to restart from snapshots and see if everything works as
expected.
I thought that based on the feedback from the community, maybe i wouldn't
need to run these tests.

Thank you.

Cordialement,

*Ghislain Rouvignac*

Email : ghr(at)sylob(dot)com

Bureau : + 33 (0)5 63 53 08 18

7, rue Marcel Dassault

ZA de la Mouline

81990 Cambon d’Albi

France

Le dim. 28 oct. 2018 à 16:35, Stephen Frost <sfrost(at)snowman(dot)net> a écrit :

> Greetings,
>
> * Ghislain ROUVIGNAC (ghr(at)sylob(dot)com) wrote:
> > Portworx says that on a running PostgreSQL it can:
> >
> > - replicate volumes for failover
> > - take snapshots of volumes
> > - backup volumes
>
> The downside with any snapshot-style approach is that it means that when
> you have a failure, you have to go through and replay all the WAL since
> the last checkpoint, which is single-threaded and can take a large
> amount of time.
>
> This is why PostgreSQL has streaming replication, where we are
> constantly sending WAL to the replica and replaying it immediately, and
> that also allows us to have synchronous replication that is quorum based
> and works with PostgreSQL, unlike what a snapshot level system would
> provide.
>
> When doing your testing, I'd strongly recommend that you have a large
> max_wal_size, run a large pgbench which writes a lot of data, and see
> how long a failover takes with this system.
>
> > Does someone use them in production ?
> > How reliable are these features ?
> > Are there performance impacts of snapshots ?
>
> I don't know anything about the actual utilization of this in production
> or if this implementation is reliable, just to be clear. My comments
> specifically are about the performance of using a snapshot-based
> approach (which could be this solution or various other ones).
>
> Thanks!
>
> Stephen
>

--
Notice de confidentialité : Les informations contenues dans ce courriel
sont strictement confidentielles et réservées à l'usage de la ou des
personne(s) identifiée(s) comme destinataire(s). L'usage, la publication,
la copie, la divulgation ou la transmission des informations contenues dans
ce message ou les documents qui y sont attachés est interdit à moins d'y
avoir été expressément autorisé par l'émetteur. Si vous avez reçu ce
message par erreur, merci de le supprimer et d'en avertir immédiatement son
expéditeur.