From: Ron <ronljohnsonjr@gmail.com>
To: pgsql-admin@lists.postgresql.org
Subject: Re: New PG14 server won't start with >2GB shared_buffers
Date: Sat, 25 Feb 2023 04:25:10 -0600
Message-ID: <4b583c4a-022f-f452-c0c8-0a932a6ee411@gmail.com> (raw)
In-Reply-To: <A446608A-42A3-4CBB-BD45-47BE009B0029@aweber.com>
References: <A446608A-42A3-4CBB-BD45-47BE009B0029@aweber.com>
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
> Email: chrish@aweber.com
>
>
>
--
Born in Arizona, moved to Babylonia.
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To: pgsql-admin@postgresql.org
Cc: ronljohnsonjr@gmail.com, pgsql-admin@lists.postgresql.org
Subject: Re: New PG14 server won't start with >2GB shared_buffers
In-Reply-To: <4b583c4a-022f-f452-c0c8-0a932a6ee411@gmail.com>
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