Re: [pve-devel] [PATCH manager] fix #4631: ceph: osd: create: add osds-per-device

[Fiona Ebner <f.ebner@proxmox.com>]

Am 18.04.23 um 14:26 schrieb Aaron Lauterer:
> Allows to automatically create multiple OSDs per physical device. The
> main use case are fast NVME drives that would be bottlenecked by a
> single OSD service.
> 
> By using the 'ceph-volume lvm batch' command instead of the 'ceph-volume
> lvm create' for multiple OSDs / device, we don't have to deal with the
> split of the drive ourselves.
> 
> But this means that the parameters to specify a DB or WAL device won't
> work as the 'batch' command doesn't use them. Dedicated DB and WAL
> devices don't make much sense anyway if we place the OSDs on fast NVME
> drives.
> 
> Some other changes to how the command is built were needed as well, as
> the 'batch' command needs the path to the disk as a positional argument,
> not as '--data /dev/sdX'.
> We drop the '--cluster-fsid' paramter because the 'batch' command
> doesn't accept it. The 'create' will fall back to reading it from the
> ceph.conf file.
> 
> Removal of OSDs works as expected without any code changes. As long as
> there are other OSDs on a disk, the VG & PV won't be removed, even if
> 'cleanup' is enabled.
> 
> Signed-off-by: Aaron Lauterer <a.lauterer@proxmox.com>
> ---

I noticed a warning while testing

--> DEPRECATION NOTICE
--> You are using the legacy automatic disk sorting behavior
--> The Pacific release will change the default to --no-auto
--> passed data devices: 1 physical, 0 LVM
--> relative data size: 0.3333333333333333

Note that I'm on Quincy, so maybe they didn't still didn't change it :P

> @@ -275,6 +275,12 @@ __PACKAGE__->register_method ({
>  		type => 'string',
>  		description => "Set the device class of the OSD in crush."
>  	    },
> +	    'osds-per-device' => {
> +		optional => 1,
> +		type => 'number',

should be integer

> +		minimum => '1',
> +		description => 'OSD services per physical device. Can improve fast NVME utilization.',

Can we add an explicit recommendation against doing it for other disk
types? I imagine it's not beneficial for those, or?

> +	    },
>  	},
>      },
>      returns => { type => 'string' },
> @@ -294,6 +300,15 @@ __PACKAGE__->register_method ({
>  	# extract parameter info and fail if a device is set more than once
>  	my $devs = {};
>  
> +	# allow 'osds-per-device' only without dedicated db and/or wal devs. We cannot specify them with
> +	# 'ceph-volume lvm batch' and they don't make a lot of sense on fast NVMEs anyway.
> +	if ($param->{'osds-per-device'}) {
> +	    for my $type ( qw(db_dev wal_dev) ) {
> +		die "Cannot use 'osds-per-device' parameter with '${type}'"

Missing newline after error message.
Could also use raise_param_exc().

> +		    if $param->{$type};
> +	    }
> +	}
> +
>  	my $ceph_conf = cfs_read_file('ceph.conf');
>  
>  	my $osd_network = $ceph_conf->{global}->{cluster_network};