Re: New PG14 server won't start with >2GB shared_buffers - Mailing list pgsql-admin

From JP Pozzi
Subject Re: New PG14 server won't start with >2GB shared_buffers
Date
Msg-id 505557535.2230.1677321184966.JavaMail.zimbra@jppozzi.dyndns.org
Whole thread Raw
In response to Re: New PG14 server won't start with >2GB shared_buffers  (Ron <ronljohnsonjr@gmail.com>)
List pgsql-admin
Hello,

Something with large pages ?

Regards


De: "Ron" <ronljohnsonjr@gmail.com>
À: "pgsql-admin" <pgsql-admin@lists.postgresql.org>
Envoyé: Samedi 25 Février 2023 11:25:10
Objet: Re: New PG14 server won't start with >2GB shared_buffers

Why did you have to drop shared buffers to 500MB, instead of something just below 2GB?

And what's "your kernel's SHMALL parameter"?

On 2/24/23 20:08, Chris Hoover wrote:
Hello All,

Have a strange issue that I can not solve.

I have a new server that has 1TB ram (not a typo).  I have been fighting with this evening to start up with a shared_buffer setting over 2GB.  When the memory allocation  breaks 2GB, the database won’t start.  I’ve dropped it down to 500M to get the database online.  We’ve tried both SysV memory and mmap memory.

Any ideas on what is going on and how to resolve?  I’m sure I’m missing something obvious, but it is totally eluding me.

OS: Ubuntu 18.04
Memory:  1007GB
CPU: Intel(R) Xeon(R) CPU           X7550  @ 2.00GHz (64 cores total)

Kernel Memory:
kernel.shmmax = 274877906944
kernel.shmall = 17179869184

Postgres Config:
                  name                                  |                  setting
 autovacuum_max_workers                 | 3
 autovacuum_work_mem                     | -1
 effective_cache_size                           | 98992128
 fsync                                                    | on
 full_page_writes                                  | on
 maintenance_work_mem                    | 2097152
 shared_buffers                                    | 64000
 shared_memory_type                         | sysv
 temp_buffers                                       | 4096
 wal_buffers                                         | 2048
 work_mem                                          | 119990

If you need additional parameters, please ask

SysV Error:
Feb 25 01:55:16 appdb-server01.production.aweberint.com postgres[34680]: FATAL:  could not create shared memory segment: Cannot allocate memory
DETAIL:  Failed system call was shmget(key=2359323, size=2063564800, 03600).
HINT:  This error usually means that PostgreSQL's request for a shared memory segment exceeded your kernel's SHMALL parameter.  You might need to reconfigure the kernel with larger SHMALL.

Mmap Error:
FATAL:  could not map anonymous shared memory: Cannot allocate memory
HINT:  This error usually means that PostgreSQL's request for a shared memory segment exceeded available memory, swap space, or huge pages. To reduce the request size (currently 1635737600 bytes), reduce PostgreSQL's shared memory usage, perhaps by reducing shared_buffers or max_connections.

Thanks,


Chris Hoover
Senior DBA
AWeber.com
Cell: (803) 528-2269




--
Born in Arizona, moved to Babylonia.

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