Re: pgBackRest for a 50 TB database

Hello,

As said above, I tested pgBackRest on my bigger DB and here are the results.
Server on which this is running has the following config:
Architecture: x86_64
CPU op-mode(s): 32-bit, 64-bit
Byte Order: Little Endian
CPU(s): 36
On-line CPU(s) list: 0-35
Thread(s) per core: 1
Core(s) per socket: 18
Socket(s): 2
NUMA node(s): 2

Data folder size: 52 TB (has some duplicate files since it is restored from
tapes)
Backup is being written on to DELL Storage, mounted on the server.

pgbackrest.conf with following options enabled
repo1-block=y
repo1-bundle=y
start-fast=y

1. *Using process-max: 30, Time taken: ~26 hours*
full backup: 20230926-092555F
timestamp start/stop: 2023-09-26 09:25:55+09 / 2023-09-27
11:07:18+09
wal start/stop: 000000010001AC0E00000044 /
000000010001AC0E00000044
database size: 38248.9GB, database backup size: 38248.9GB
repo1: backup size: 6222.0GB

2. *Using process-max: 10, Time taken: ~37 hours*
full backup: 20230930-190002F
timestamp start/stop: 2023-09-30 19:00:02+09 / 2023-10-02
08:01:20+09
wal start/stop: 000000010001AC0E0000004E /
000000010001AC0E0000004E
database size: 38248.9GB, database backup size: 38248.9GB
repo1: backup size: 6222.0GB

Hope it helps someone to use these numbers as some reference.

Thanks

On Mon, Aug 28, 2023 at 12:30 AM Abhishek Bhola <
abhishek(dot)bhola(at)japannext(dot)co(dot)jp> wrote:

> Hi Stephen
>
> Thank you for the prompt response.
> Hearing it from you makes me more confident about rolling it to PROD.
> I will have a discussion with the network team once about and hear what
> they have to say and make an estimate accordingly.
>
> If you happen to know anyone using it with that size and having published
> their numbers, that would be great, but if not, I will post them once I set
> it up.
>
> Thanks for your help.
>
> Cheers,
> Abhishek
>
> On Mon, Aug 28, 2023 at 12:22 AM Stephen Frost <sfrost(at)snowman(dot)net> wrote:
>
>> Greetings,
>>
>> * Abhishek Bhola (abhishek(dot)bhola(at)japannext(dot)co(dot)jp) wrote:
>> > I am trying to use pgBackRest for all my Postgres servers. I have
>> tested it
>> > on a sample database and it works fine. But my concern is for some of
>> the
>> > bigger DB clusters, the largest one being 50TB and growing by about
>> > 200-300GB a day.
>>
>> Glad pgBackRest has been working well for you.
>>
>> > I plan to mount NAS storage on my DB server to store my backup. The
>> server
>> > with 50 TB data is using DELL Storage underneath to store this data and
>> has
>> > 36 18-core CPUs.
>>
>> How much free CPU capacity does the system have?
>>
>> > As I understand, pgBackRest recommends having 2 full backups and then
>> > having incremental or differential backups as per requirement. Does
>> anyone
>> > have any reference numbers on how much time a backup for such a DB would
>> > usually take, just for reference. If I take a full backup every Sunday
>> and
>> > then incremental backups for the rest of the week, I believe the
>> > incremental backups should not be a problem, but the full backup every
>> > Sunday might not finish in time.
>>
>> pgBackRest scales extremely well- what's going to matter here is how
>> much you can give it in terms of resources. The primary bottle necks
>> will be CPU time for compression, network bandwidth for the NAS, and
>> storage bandwidth of the NAS and the DB filesystems. Typically, CPU
>> time dominates due to the compression, though if you're able to give
>> pgBackRest a lot of those CPUs then you might get to the point of
>> running out of network bandwidth or storage bandwidth on your NAS.
>> We've certainly seen folks pushing upwards of 3TB/hr, so a 50TB backup
>> should be able to complete in less than a day. Strongly recommend
>> taking an incremental backup more-or-less immediately after the full
>> backup to minimize the amount of WAL you'd have to replay on a restore.
>> Also strongly recommend actually doing serious restore tests of this
>> system to make sure you understand the process, have an idea how long
>> it'll take to restore the actual files with pgBackRest and then how long
>> PG will take to come up and replay the WAL generated during the backup.
>>
>> > I think converting a diff/incr backup to a full backup has been
>> discussed
>> > here <https://github.com/pgbackrest/pgbackrest/issues/644>, but not yet
>> > implemented. If there is a workaround, please let me know. Or if
>> someone is
>> > simply using pgBackRest for a bigger DB (comparable to 50TB), please
>> share
>> > your experience with the exact numbers and config/schedule of backups. I
>> > know the easiest way would be to use it myself and find out, but since
>> it
>> > is a PROD DB, I wanted to get some ideas before starting.
>>
>> No, we haven't implemented that yet. It's starting to come up higher in
>> our list of things we want to work on though. There are risks to doing
>> such conversions though that have to be considered- it creates long
>> dependencies on things all working because if there's a PG or pgBackRest
>> bug or some way that corruption slipped in then that ends up getting
>> propagated down. If you feel really confident that your restore testing
>> is good (full restore w/ PG replaying WAL, running amcheck across the
>> entire restored system, then pg_dump'ing everything and restoring it
>> into a new PG cluster to re-validate all constraints, doing additional
>> app-level review and testing...) then that can certainly help with
>> mitigation of the risks mentioned above.
>>
>> Overall though, yes, people certainly use pgBackRest for 50TB+ PG
>> clusters.
>>
>> Thanks,
>>
>> Stephen
>>
>

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