Creating Lustre Object Storage Services (OSS) - Revision history

Adilger: /* Formatting an OST using only the mkfs.lustre command */ reference ZFS Tunables page

2018-05-25T20:24:44Z

Formatting an OST using only the mkfs.lustre command: reference ZFS Tunables page

← Older revision		Revision as of 13:24, 25 May 2018
Line 105:		Line 105:
	=== Formatting an OST using only the mkfs.lustre command ===		=== Formatting an OST using only the mkfs.lustre command ===

	'''Note:''' For the greatest flexibility and control when creating ZFS-based Lustre storage targets, do not use this approach – instead, create the zpool separately from formatting the Lustre OSD. See [[#Formatting an OST using zpool and mkfs.lustre\|Formatting an OST using zpool and mkfs.lustre]].		'''Note:''' For the greatest flexibility and control when creating ZFS-based Lustre storage targets, do not use this approach – instead, create the zpool separately from formatting the Lustre OSD. See [[#Formatting an OST using zpool and mkfs.lustre\|Formatting an OST using zpool and mkfs.lustre]]. See also [[ZFS_Tunables_for_Lustre_Object_Storage_Servers_(OSS)]] for ZFS-specific tuning options.

	The syntax for creating a ZFS-based OST using only the <code>mkfs.lustre</code> command is:		The syntax for creating a ZFS-based OST using only the <code>mkfs.lustre</code> command is:

Malcolm: /* Formatting an OST using zpool and mkfs.lustre */

2017-10-11T05:19:20Z

Formatting an OST using zpool and mkfs.lustre

← Older revision		Revision as of 22:19, 10 October 2017
Line 259:		Line 259:
	lustre:mgsnode=192.168.227.11@tcp1:192.168.227.12@tcp1		lustre:mgsnode=192.168.227.11@tcp1:192.168.227.12@tcp1
	lustre:failover.node=192.168.227.21@tcp1:192.168.227.22@tcp1		lustre:failover.node=192.168.227.21@tcp1:192.168.227.22@tcp1
	<pre ~~style="overflow-x:auto;"~~>		</pre>

	Refer to [[ZFS recordsize Property]] for recommendations on how to set the recordsize appropriately.		Refer to [[ZFS recordsize Property]] for recommendations on how to set the recordsize appropriately.

Malcolm: /* Formatting an OST using only the mkfs.lustre command */

2017-09-22T00:10:20Z

Formatting an OST using only the mkfs.lustre command

← Older revision		Revision as of 17:10, 21 September 2017
Line 155:		Line 155:
	The <code>--failnode</code> syntax is similar, but is used to define only a failover target for the storage service. For example:		The <code>--failnode</code> syntax is similar, but is used to define only a failover target for the storage service. For example:

			<pre style="overflow-x:auto;">
	[root@rh7z-oss1 system]# mkfs.lustre --ost \		[root@rh7z-oss1 system]# mkfs.lustre --ost \
	> --fsname demo --index 0 \		> --fsname demo --index 0 \
Line 161:		Line 162:
	> --backfstype=zfs \		> --backfstype=zfs \
	> demo-ost0pool/ost0 mirror sdb sdd		> demo-ost0pool/ost0 mirror sdb sdd
			</pre>

	'''Note:''': When creating a ZFS-based OSD using only the <code>mkfs.lustre</code> command, it is not possible to set or change some properties of the zpool or its vdevs, such as the <code>multihost</code> and <code>ashift</code> properties. For this reason, it is highly recommended that the zpools be created independently of the <code>mkfs.lustre</code> command, as shown in the next section.		'''Note:''': When creating a ZFS-based OSD using only the <code>mkfs.lustre</code> command, it is not possible to set or change some properties of the zpool or its vdevs, such as the <code>multihost</code> and <code>ashift</code> properties. For this reason, it is highly recommended that the zpools be created independently of the <code>mkfs.lustre</code> command, as shown in the next section.

Malcolm: /* OST Formatted as a ZFS OSD */

2017-09-13T02:04:43Z

OST Formatted as a ZFS OSD

← Older revision		Revision as of 19:04, 12 September 2017
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	> --servicenode 192.168.227.22@tcp1 \		> --servicenode 192.168.227.22@tcp1 \
	> --backfstype=zfs \		> --backfstype=zfs \
	> --mkfsoptions "recordsize=1024K" \		> --mkfsoptions "recordsize=1024K -o compression=lz4" \
	> demo-ost0pool/ost0 \		> demo-ost0pool/ost0 \
	> raidz2 sda sdb sdc sdd sde sdf		> raidz2 sda sdb sdc sdd sde sdf
Line 148:		Line 148:

	<pre style="overflow-x:auto;">		<pre style="overflow-x:auto;">
	--mkfsoptions="recordsize=1024K -o mountpoint=none"		--mkfsoptions="recordsize=1024K -o compression=lz4 -o mountpoint=none"
	</pre>		</pre>

	Refer to [[ZFS recordsize Property]] for recommendations on how to set the recordsize appropriately.		Refer to [[ZFS recordsize Property]] for recommendations on how to set the <code>compression</code> and <code>recordsize</code> properties appropriately.

	The <code>--failnode</code> syntax is similar, but is used to define only a failover target for the storage service. For example:		The <code>--failnode</code> syntax is similar, but is used to define only a failover target for the storage service. For example:
Line 172:		Line 172:
	-O canmount=off \		-O canmount=off \
	-O recordsize=<RK> \		-O recordsize=<RK> \
			-O compression=lz4\|on \
	[-o ashift=<n>] \		[-o ashift=<n>] \
	-o cachefile=/etc/zfs/<zpool name>.spec \| -o cachefile=none \		-o cachefile=/etc/zfs/<zpool name>.spec \| -o cachefile=none \
Line 195:		Line 196:
	# Pool will comprise a single RAIDZ2 vdev with 6 devices		# Pool will comprise a single RAIDZ2 vdev with 6 devices
	# Recordsize is set to 1024K		# Recordsize is set to 1024K
			# Compression is enabled and set to use lz4 algorithm
	zpool create -o multihost=on \		zpool create -o multihost=on \
	-O canmount=off \		-O canmount=off \
	-O recordsize=1024K \		-O recordsize=1024K \
			-O compression=lz4 \
	-o cachefile=none \		-o cachefile=none \
	demo-ost0pool \		demo-ost0pool \
Line 220:		Line 223:
	> -O canmount=off \		> -O canmount=off \
	> -O recordsize=1024K \		> -O recordsize=1024K \
			> -O compression=lz4 \
	> -o cachefile=none \		> -o cachefile=none \
	> demo-ost0pool \		> demo-ost0pool \
Line 263:		Line 267:
	NAME PROPERTY VALUE SOURCE		NAME PROPERTY VALUE SOURCE
	demo-ost0pool recordsize 1M local		demo-ost0pool recordsize 1M local
			demo-ost0pool compression lz4 local
	demo-ost0pool canmount off local		demo-ost0pool canmount off local
	demo-ost0pool/ost0 recordsize 1M inherited from demo-ost0pool		demo-ost0pool/ost0 recordsize 1M inherited from demo-ost0pool
			demo-ost0pool/ost0 compression lz4 inherited from demo-ost0pool
	demo-ost0pool/ost0 canmount off local		demo-ost0pool/ost0 canmount off local
	demo-ost0pool/ost0 xattr sa local		demo-ost0pool/ost0 xattr sa local

Malcolm: /* OST Formatted as a ZFS OSD */

2017-09-11T05:20:22Z

OST Formatted as a ZFS OSD

← Older revision		Revision as of 22:20, 10 September 2017
Line 162:		Line 162:
	> demo-ost0pool/ost0 mirror sdb sdd		> demo-ost0pool/ost0 mirror sdb sdd

	'''Note:''': When creating a ZFS-based OSD using only the <code>mkfs.lustre</code> command, it is not possible to set or change some properties of the zpool or its vdevs, such as the <code>ashift</code> ~~property~~. For this reason, it is highly recommended that the zpools be created independently of the <code>mkfs.lustre</code> command, as shown in the next section.		'''Note:''': When creating a ZFS-based OSD using only the <code>mkfs.lustre</code> command, it is not possible to set or change some properties of the zpool or its vdevs, such as the <code>multihost</code> and <code>ashift</code> properties. For this reason, it is highly recommended that the zpools be created independently of the <code>mkfs.lustre</code> command, as shown in the next section.

	=== Formatting an OST using zpool and mkfs.lustre ===		=== Formatting an OST using zpool and mkfs.lustre ===
Line 169:		Line 169:

	<pre style="overflow-x:auto;">		<pre style="overflow-x:auto;">
	zpool create [-f] \		zpool create [-f] -o multihost=on \
	-O canmount=off \		-O canmount=off \
	-O recordsize=<RK> \		-O recordsize=<RK> \
Line 195:		Line 195:
	# Pool will comprise a single RAIDZ2 vdev with 6 devices		# Pool will comprise a single RAIDZ2 vdev with 6 devices
	# Recordsize is set to 1024K		# Recordsize is set to 1024K
	zpool create \		zpool create -o multihost=on \
	-O canmount=off \		-O canmount=off \
	-O recordsize=1024K \		-O recordsize=1024K \
Line 217:		Line 217:
	<pre style="overflow-x:auto;">		<pre style="overflow-x:auto;">
	# The zpool command will not return output unless there are errors		# The zpool command will not return output unless there are errors
	[root@rh7z-oss1 system]# zpool create \		[root@rh7z-oss1 system]# zpool create -o multihost=on \
	> -O canmount=off \		> -O canmount=off \
	> -O recordsize=1024K \		> -O recordsize=1024K \

Malcolm at 05:54, 31 August 2017

2017-08-31T05:54:15Z

← Older revision		Revision as of 22:54, 30 August 2017
Line 361:		Line 361:

	[[Category:Creating Lustre File System Services]]		[[Category:Creating Lustre File System Services]]
			[[Category:Lustre Systems Administration]]

Malcolm: Created page with "== Syntax Overview == The syntax for creating an OST is:

 mkfs.lustre --ost \   [--reformat] \   --fsname  \   --index  \   --mgsnode..."

2017-08-16T05:32:00Z

Created page with "== Syntax Overview == The syntax for creating an OST is: <pre style="overflow-x:auto;"> mkfs.lustre --ost \ [--reformat] \ --fsname <name> \ --index <n> \ --mgsnode..."

New page

== Syntax Overview ==

The syntax for creating an OST is:

<pre style="overflow-x:auto;">
mkfs.lustre --ost \
[--reformat] \
--fsname <name> \
--index <n> \
--mgsnode <MGS NID> [--mgsnode <MGS NID> …] \
[ --servicenode <NID> [--servicenode <NID> …]] \
[ --failnode <NID> [--failnode <NID> …]] \
[ --backfstype=ldiskfs|zfs ] \
[ --mkfsoptions <options> ] \
<device path> | <pool name>/<dataset> <zpool specification>
</pre>

The command line syntax for formatting an OST is very similar to that for the [[Creating the Lustre Metadata Service (MDS)|MDT]]. To create an OST, the <code>mkfs.lustre</code> command requires the file system name, OST index, list of MGS server NIDs, and the NIDS for each of the OSS machines that can mount the OST (used for HA failover). The command also specifies the back-end file system type and device path or ZFS pool.

The MGS NIDs are supplied using the <code>--mgsnode</code> flag. If there is more than one potential location for the MGS (i.e., it is part of a high availability failover cluster configuration), then the option is repeated for as many failover nodes as are configured (usually there are two).

Ordering of the MGS nodes in the command line is significant: the first <code>--mgsnode</code> flag must reference the NID of the current active or primary MGS server. If this is not the case, then the first time that the OST tries to join the cluster, it will fail. The first time mount of a storage target does not currently check the failover locations when trying to establish a connection with the MGS. When adding new storage targets to Lustre, the MGS must be running on its primary NID.

Each OST must also be supplied with the name (<code>--fsname</code>) of the Lustre file system it will join (maximum 8 characters), and an index number (<code>--index</code>) unique to the file system.

The list of service nodes (<code>--servicenode</code>) or failover nodes (<code>--failnode</code>) must be specified for any high availability configuration. Although there are more compact declarations for defining the nodes, for simplicity, list the NID of each server that can mount the storage as a separate <code>--servicenode</code> entry.

The next example uses the <code>--servicenode</code> syntax to create an OST that can be run on two servers as an HA failover resource:

<pre style="overflow-x:auto;">
[root@rh7z-oss1 system]# mkfs.lustre --ost \
> --fsname demo \
> --index 0 \
> --mgsnode 192.168.227.11@tcp1 \
> --mgsnode 192.168.227.12@tcp1 \
> --servicenode 192.168.227.21@tcp1 \
> --servicenode 192.168.227.22@tcp1 \
> /dev/dm-3
</pre>

The command line formats a new OST that will be used by an OSS for storage. The OST will be part of a file system called <code>demo</code>, with index number <code>0</code> (zero). There are two NIDs defined as the nodes able to host the OSS service, denoted by the <code>--servicenode</code> options, and two NIDs supplied for the MGS that the OSS will register with.

The <code>--failnode</code> syntax is similar, but is used to define only a failover target for the storage service. For example:

<pre style="overflow-x:auto;">
[root@rh7z-oss1 system]# mkfs.lustre --ost \
> --fsname demo \
> --index 0 \
> --mgsnode 192.168.227.11@tcp1 \
> --mgsnode 192.168.227.12@tcp1 \
> --failnode 192.168.227.22@tcp1 \
> /dev/dm-3
</pre>

Here, the failover host is identified as <code>192.168.227.22@tcp1</code>, one server in an HA pair (and which, for the purpose of this example, has the hostname <code>rh7z-oss2</code>). The <code>mkfs.lustre</code> command was executed on <code>rh7z-oss1</code> (NID: <code>192.168.227.21@tcp1</code>), and the <code>mount</code> command must also be run from this host when the service starts for the very first time.

== OST Formatted as an LDISKFS OSD ==

The syntax for creating an LDISKFS-based OST is:

<pre style="overflow-x:auto;">
mkfs.lustre --ost \
[--reformat] \
--fsname <name> \
--index <n> \
--mgsnode <MGS NID> [--mgsnode <MGS NID> …] \
[ --servicenode <NID> [--servicenode <NID> …]] \
[ --failnode <NID> [--failnode <NID> …]] \
[ --backfstype=ldiskfs ] \
[ --mkfsoptions <options> ] \
<device path>
</pre>

The next example uses the <code>--servicenode</code> syntax to create an OST that can be run on two servers as an HA failover resource:

<pre style="overflow-x:auto;">
[root@rh7z-oss1 system]# mkfs.lustre --ost \
> --fsname demo \
> --index 0 \
> --mgsnode 192.168.227.11@tcp1 \
> --mgsnode 192.168.227.12@tcp1 \
> --servicenode 192.168.227.21@tcp1 \
> --servicenode 192.168.227.22@tcp1 \
> --backfstype=ldiskfs \
> /dev/dm-3
</pre>

The <code>--failnode</code> syntax is similar, but is used to define only a failover target for the storage service. For example:

<pre style="overflow-x:auto;">
[root@rh7z-oss1 system]# mkfs.lustre --ost \
> --fsname demo \
> --index 0 \
> --mgsnode 192.168.227.11@tcp1 \
> --mgsnode 192.168.227.12@tcp1 \
> --failnode 192.168.227.22@tcp1 \
> --backfstype=ldiskfs \
> /dev/dm-3
</pre>

The above examples are repeated from the main introduction to the syntax, but are included here to maintain symmetry with the rest of the text. However, note that the <code>--backfstype</code> flag has been set to <code>ldiskfs</code>, which tells <code>mkfs.lustre</code> to format the device as an LDISKFS OSD.

== OST Formatted as a ZFS OSD ==

=== Formatting an OST using only the mkfs.lustre command ===

'''Note:''' For the greatest flexibility and control when creating ZFS-based Lustre storage targets, do not use this approach – instead, create the zpool separately from formatting the Lustre OSD. See [[#Formatting an OST using zpool and mkfs.lustre|Formatting an OST using zpool and mkfs.lustre]].

The syntax for creating a ZFS-based OST using only the <code>mkfs.lustre</code> command is:

<pre style="overflow-x:auto;">
mkfs.lustre --ost \
[--reformat] \
--fsname <name> \
--index <n> \
--mgsnode <MGS NID> [--mgsnode <MGS NID> …] \
[ --servicenode <NID> [--servicenode <NID> …]] \
[ --failnode <NID> [--failnode <NID> …]] \
--backfstype=zfs \
[ --mkfsoptions <options> ] \
<pool name>/<dataset> \
<zpool specification>
</pre>

The next example uses the <code>--servicenode</code> syntax to create an OST that can be run on two servers as an HA failover resource:

<pre style="overflow-x:auto;">
[root@rh7z-oss1 system]# mkfs.lustre --ost \
> --fsname demo \
> --index 0 \
> --mgsnode 192.168.227.11@tcp1 \
> --mgsnode 192.168.227.12@tcp1 \
> --servicenode 192.168.227.21@tcp1 \
> --servicenode 192.168.227.22@tcp1 \
> --backfstype=zfs \
> --mkfsoptions "recordsize=1024K" \
> demo-ost0pool/ost0 \
> raidz2 sda sdb sdc sdd sde sdf
</pre>

The command line formats a new ZFS-based OST that will be used by an OSS for storage. The OST will be part of to a file system called <code>demo</code>, with index number <code>0</code> (zero). The back-end storage is a ZFS pool called <code>demo-ost0pool</code> comprising a RAIDZ2 vdev constructed from six physical devices, and creates a ZFS file system dataset called <code>ost0</code>. Two server NIDs are supplied as service nodes for the OSS, <code>192.168.227.21@tcp1</code> and <code>192.168.227.22@tcp1</code>, and there are NIDs for the MGS primary and failover hosts.

In the above command-line, notice that there is a custom property for the recordsize, set using <code>--mkfsoptions "recordsize=1024K"</code>. The syntax of string needs some explanation.

The <code>mkfs.lustre</code> command takes the string provided as an argument to <code>--mkfsoptions</code>, prefixes the string with <code>-o</code> and inserts it into the <code>zfs</code> command line that creates the dataset. This can be observed in the output of the <code>mkfs.lustre</code> command.

If only one property is being altered, then just create the <code><name>=<value></code> pair string without any additional flags or arguments. However, if more than one property needs to be set, then separate each property with <code>-o</code>. For example:

<pre style="overflow-x:auto;">
--mkfsoptions="recordsize=1024K -o mountpoint=none"
</pre>

Refer to [[ZFS recordsize Property]] for recommendations on how to set the recordsize appropriately.

The <code>--failnode</code> syntax is similar, but is used to define only a failover target for the storage service. For example:

[root@rh7z-oss1 system]# mkfs.lustre --ost \
> --fsname demo --index 0 \
> --mgsnode 192.168.227.11@tcp1 --mgsnode 192.168.227.12@tcp1 \
> --failnode 192.168.227.22@tcp1 \
> --backfstype=zfs \
> demo-ost0pool/ost0 mirror sdb sdd

'''Note:''': When creating a ZFS-based OSD using only the <code>mkfs.lustre</code> command, it is not possible to set or change some properties of the zpool or its vdevs, such as the <code>ashift</code> property. For this reason, it is highly recommended that the zpools be created independently of the <code>mkfs.lustre</code> command, as shown in the next section.

=== Formatting an OST using zpool and mkfs.lustre ===

To create a ZFS-based OST, create a zpool to contain the OST file system dataset, then use <code>mkfs.lustre</code> to create the actual file system dataset inside the zpool:

<pre style="overflow-x:auto;">
zpool create [-f] \
-O canmount=off \
-O recordsize=<RK> \
[-o ashift=<n>] \
-o cachefile=/etc/zfs/<zpool name>.spec | -o cachefile=none \
<zpool name> \
<zpool specification>

mkfs.lustre --ost \
[--reformat] \
--fsname <name> \
--index <n> \
--mgsnode <MGS NID> [--mgsnode <MGS NID> …] \
[ --servicenode <NID> [--servicenode <NID> …]] \
[ --failnode <NID> [--failnode <NID> …]] \
--backfstype=zfs \
[ --mkfsoptions <options> ] \
<pool name>/<dataset>
</pre>

For example:

<pre style="overflow-x:auto;">
# Create the zpool
# Pool will comprise a single RAIDZ2 vdev with 6 devices
# Recordsize is set to 1024K
zpool create \
-O canmount=off \
-O recordsize=1024K \
-o cachefile=none \
demo-ost0pool \
raidz2 sda sdb sdc sdd sde sdf

# Format OST0 for Lustre file system "demo"
mkfs.lustre --ost \
--fsname demo \
--index 0 \
--mgsnode 192.168.227.11@tcp1 --mgsnode 192.168.227.12@tcp1 \
--servicenode 192.168.227.21@tcp1 \
--servicenode 192.168.227.22@tcp1 \
--backfstype=zfs \
demo-ost0pool/ost0
</pre>

The output from the above example will look something like this:

<pre style="overflow-x:auto;">
# The zpool command will not return output unless there are errors
[root@rh7z-oss1 system]# zpool create \
> -O canmount=off \
> -O recordsize=1024K \
> -o cachefile=none \
> demo-ost0pool \
> raidz2 sda sdb sdc sdd sde sdf

[root@rh7z-oss1 lz]# mkfs.lustre --ost \
> --fsname demo \
> --index 0 \
> --mgsnode 192.168.227.11@tcp1 --mgsnode 192.168.227.12@tcp1 \
> --servicenode 192.168.227.21@tcp1 \
> --servicenode 192.168.227.22@tcp1 \
> --backfstype=zfs \
> demo-ost0pool/ost0

Permanent disk data:
Target: demo:OST0000
Index: 0
Lustre FS: demo
Mount type: zfs
Flags: 0x1062
(OST first_time update no_primnode )
Persistent mount opts:
Parameters: mgsnode=192.168.227.11@tcp1:192.168.227.12@tcp1 failover.node=192.168.227.21@tcp1:192.168.227.22@tcp1

checking for existing Lustre data: not found
mkfs_cmd = zfs create -o canmount=off -o xattr=sa demo-ost0pool/ost0
Writing demo-ost0pool/ost0 properties
lustre:version=1
lustre:flags=4194
lustre:index=0
lustre:fsname=demo
lustre:svname=demo:OST0000
lustre:mgsnode=192.168.227.11@tcp1:192.168.227.12@tcp1
lustre:failover.node=192.168.227.21@tcp1:192.168.227.22@tcp1
<pre style="overflow-x:auto;">

Refer to [[ZFS recordsize Property]] for recommendations on how to set the recordsize appropriately.

Use the <code>zfs get</code> command or <code>tunefs.lustre</code> to verify that the file system dataset has been formatted correctly. For example:

<pre style="overflow-x:auto;">
[root@rh7-oss1 ~]# zfs get all -s local,inherited
NAME PROPERTY VALUE SOURCE
demo-ost0pool recordsize 1M local
demo-ost0pool canmount off local
demo-ost0pool/ost0 recordsize 1M inherited from demo-ost0pool
demo-ost0pool/ost0 canmount off local
demo-ost0pool/ost0 xattr sa local
demo-ost0pool/ost0 lustre:mgsnode 192.168.227.11@tcp1:192.168.227.12@tcp1 local
demo-ost0pool/ost0 lustre:flags 4194 local
demo-ost0pool/ost0 lustre:fsname demo local
demo-ost0pool/ost0 lustre:version 1 local
demo-ost0pool/ost0 lustre:failover.node 192.168.227.21@tcp1:192.168.227.22@tcp1 local
demo-ost0pool/ost0 lustre:index 0 local
demo-ost0pool/ost0 lustre:svname demo:OST0000 local
</pre>

== Starting the OSS Service ==

The <code>mount</code> command is used to start all Lustre storage services, including the OSS. The syntax is:

<pre style="overflow-x:auto;">
mount -t lustre [-o <options>] \
<ldiskfs blockdev>|<zpool>/<dataset> <mount point>
</pre>

The <code>mount</code> command syntax is very similar for both LDISKFS and ZFS storage targets. The main difference is the format of the path to the storage. For LDISKFS, the path will resolve to a block device, such as <code>/dev/sda</code> or <code>/dev/mapper/mpatha</code>, whereas for ZFS, the path resolves to a dataset in a zpool, e.g. <code>demo-mdt0pool/mdt0</code>.

The mount point directory must exist before the mount command is executed. The recommended convention for the mount point of the OST storage is <code>/lustre/<fsname>/ost<n></code>, where <code><fsname></code> is the name of the file system and <code><n></code> is the index number of the OST.

The following example starts a ZFS-based OSS:

<pre style="overflow-x:auto;">
[root@rh7z-oss1 ~]# zfs list -o name,used,avail,refer
NAME USED AVAIL REFER
demo-ost0pool 173M 48.0G 19K
demo-ost0pool/ost0 173M 48.0G 173M

[root@rh7z-oss1 lz]# mkdir -p /lustre/demo/ost0
[root@rh7z-oss1 lz]# mount -t lustre demo-ost0pool/ost0 /lustre/demo/ost0

[root@rh7z-oss1 lz]# df -ht lustre
File system Size Used Avail Use% Mounted on
demo-ost0pool/ost0 49G 2.9M 49G 1% /lustre/demo/ost0
</pre>

As with all Lustre storage targets, only the <code>mount -t lustre</code> command can start Lustre services.

To verify that the OSS is running, check that the device has been mounted, then get the Lustre device list with <code>lctl dl</code> and review the running processes:

<pre style="overflow-x:auto;">
[root@rh7z-oss1 lz]# lctl dl
0 UP osd-zfs demo-OST0000-osd demo-OST0000-osd_UUID 5
1 UP mgc MGC192.168.227.11@tcp1 4106d169-ed51-cd92-3361-12800a73962d 5
2 UP ost OSS OSS_uuid 3
3 UP obdfilter demo-OST0000 demo-OST0000_UUID 7
4 UP lwp demo-MDT0000-lwp-OST0000 demo-MDT0000-lwp-OST0000_UUID 5

[root@rh7z-oss1 lz]# ps -ef | awk '/ost/ && !/awk/'
root 1932 1 0 Apr04 ? 00:00:00 /usr/libexec/postfix/master -w
postfix 1984 1932 0 Apr04 ? 00:00:00 pickup -l -t unix -u
postfix 1985 1932 0 Apr04 ? 00:00:00 qmgr -l -t unix -u
root 24709 2 0 00:03 ? 00:00:00 [ll_ost00_000]
root 24710 2 0 00:03 ? 00:00:00 [ll_ost00_001]
root 24711 2 0 00:03 ? 00:00:00 [ll_ost00_002]
root 24712 2 0 00:03 ? 00:00:00 [ll_ost_create00]
root 24713 2 0 00:03 ? 00:00:00 [ll_ost_create00]
root 24714 2 0 00:03 ? 00:00:00 [ll_ost_io00_000]
root 24715 2 0 00:03 ? 00:00:00 [ll_ost_io00_001]
root 24716 2 0 00:03 ? 00:00:00 [ll_ost_io00_002]
root 24717 2 0 00:03 ? 00:00:00 [ll_ost_seq00_00]
root 24718 2 0 00:03 ? 00:00:00 [ll_ost_seq00_00]
root 24719 2 0 00:03 ? 00:00:00 [ll_ost_out00_00]
root 24720 2 0 00:03 ? 00:00:00 [ll_ost_out00_00]
</pre>

== Stopping the OSS Service ==

To stop a Lustre service, umount the corresponding target:

<pre style="overflow-x:auto;">
umount <mount point>
</pre>

The mount point must correspond to the mount point used with the <code>mount -t lustre</code> command. For example:

<pre style="overflow-x:auto;">
[root@rh7z-oss1 lz]# df -ht lustre
File system Size Used Avail Use% Mounted on
demo-ost0pool/ost0 49G 2.9M 49G 1% /lustre/demo/ost0
[root@rh7z-oss1 ~]# umount /lustre/demo/ost0
[root@rh7z-oss1 ~]# df -ht lustre
df: no file systems processed
[root@rh7z-oss1 ~]# lctl dl
[root@rh7z-oss1 ~]#
</pre>

The regular <code>umount</code> command is the correct way to stop a given Lustre service and unmount the associated storage, for both LDISKFS and ZFS-based Lustre storage volumes.

Do not use the <code>zfs unmount</code> command to stop a Lustre service. Attempting to use <code>zfs</code> commands to unmount a storage target that is mounted as part of an active Lustre service will return an error.

[[Category:Creating Lustre File System Services]]