[pve-devel] [PATCH manager v2] fix #4631: ceph: osd: create: add osds-per-device

[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.

The '--no-auto' paramter is used to avoid the following deprecation
warning:
```
--> 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
```

Signed-off-by: Aaron Lauterer <a.lauterer at proxmox.com>
---
changes since v1:
* change parameter type to integer
* rephrase parameter description to make it clear it is only useful for
NVMEs
* change error handling to raise_param_exc
* add --no-auto param to ceph-volume

 PVE/API2/Ceph/OSD.pm | 28 ++++++++++++++++++++++++----
 1 file changed, 24 insertions(+), 4 deletions(-)

diff --git a/PVE/API2/Ceph/OSD.pm b/PVE/API2/Ceph/OSD.pm
index ded35990..3a51bebc 100644
--- a/PVE/API2/Ceph/OSD.pm
+++ b/PVE/API2/Ceph/OSD.pm
@@ -275,6 +275,13 @@ __PACKAGE__->register_method ({
 		type => 'string',
 		description => "Set the device class of the OSD in crush."
 	    },
+	    'osds-per-device' => {
+		optional => 1,
+		type => 'integer',
+		minimum => '1',
+		description => 'OSD services per physical device. Only useful for fast ".
+		    "NVME devices to utilize their performance better.',
+	    },
 	},
     },
     returns => { type => 'string' },
@@ -294,6 +301,15 @@ __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) ) {
+		raise_param_exc({ $type => "canot use 'osds-per-device' parameter with '${type}'" })
+		    if $param->{$type};
+	    }
+	}
+
 	my $ceph_conf = cfs_read_file('ceph.conf');
 
 	my $osd_network = $ceph_conf->{global}->{cluster_network};
@@ -364,8 +380,6 @@ __PACKAGE__->register_method ({
 	my $monstat = $rados->mon_command({ prefix => 'quorum_status' });
 
 	die "unable to get fsid\n" if !$monstat->{monmap} || !$monstat->{monmap}->{fsid};
-	my $fsid = $monstat->{monmap}->{fsid};
-        $fsid = $1 if $fsid =~ m/^([0-9a-f\-]+)$/;
 
 	my $ceph_bootstrap_osd_keyring = PVE::Ceph::Tools::get_config('ceph_bootstrap_osd_keyring');
 
@@ -470,7 +484,10 @@ __PACKAGE__->register_method ({
 		$test_disk_requirements->($disklist);
 
 		my $dev_class = $param->{'crush-device-class'};
-		my $cmd = ['ceph-volume', 'lvm', 'create', '--cluster-fsid', $fsid ];
+		# create allows for detailed configuration of DB and WAL devices
+		# batch for easy creation of multiple OSDs (per device)
+		my $create_mode = $param->{'osds-per-device'} ? 'batch' : 'create';
+		my $cmd = ['ceph-volume', 'lvm', $create_mode ];
 		push @$cmd, '--crush-device-class', $dev_class if $dev_class;
 
 		my $devname = $devs->{dev}->{name};
@@ -504,8 +521,11 @@ __PACKAGE__->register_method ({
 		    push @$cmd, "--block.$type", $part_or_lv;
 		}
 
-		push @$cmd, '--data', $devpath;
+		push @$cmd, '--data' if $create_mode eq 'create';
+		push @$cmd, $devpath;
 		push @$cmd, '--dmcrypt' if $param->{encrypted};
+		push @$cmd, '--osds-per-device', $param->{'osds-per-device'}, '--yes', '--no-auto'
+		    if $create_mode eq 'batch';
 
 		PVE::Diskmanage::wipe_blockdev($devpath);
 
-- 
2.39.2