Creating Lustre Object Storage Services (OSS): Difference between revisions
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[[Category:Creating Lustre File System Services]] | [[Category:Creating Lustre File System Services]] | ||
[[Category:Lustre Systems Administration]] |
Revision as of 22:54, 30 August 2017
Syntax Overview
The syntax for creating an OST is:
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>
The command line syntax for formatting an OST is very similar to that for the MDT. To create an OST, the mkfs.lustre
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 --mgsnode
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 --mgsnode
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 (--fsname
) of the Lustre file system it will join (maximum 8 characters), and an index number (--index
) unique to the file system.
The list of service nodes (--servicenode
) or failover nodes (--failnode
) 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 --servicenode
entry.
The next example uses the --servicenode
syntax to create an OST that can be run on two servers as an HA failover resource:
[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
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 demo
, with index number 0
(zero). There are two NIDs defined as the nodes able to host the OSS service, denoted by the --servicenode
options, and two NIDs supplied for the MGS that the OSS will register with.
The --failnode
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 \ > /dev/dm-3
Here, the failover host is identified as 192.168.227.22@tcp1
, one server in an HA pair (and which, for the purpose of this example, has the hostname rh7z-oss2
). The mkfs.lustre
command was executed on rh7z-oss1
(NID: 192.168.227.21@tcp1
), and the mount
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:
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>
The next example uses the --servicenode
syntax to create an OST that can be run on two servers as an HA failover resource:
[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
The --failnode
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=ldiskfs \ > /dev/dm-3
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 --backfstype
flag has been set to ldiskfs
, which tells mkfs.lustre
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.
The syntax for creating a ZFS-based OST using only the mkfs.lustre
command is:
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>
The next example uses the --servicenode
syntax to create an OST that can be run on two servers as an HA failover resource:
[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
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 demo
, with index number 0
(zero). The back-end storage is a ZFS pool called demo-ost0pool
comprising a RAIDZ2 vdev constructed from six physical devices, and creates a ZFS file system dataset called ost0
. Two server NIDs are supplied as service nodes for the OSS, 192.168.227.21@tcp1
and 192.168.227.22@tcp1
, 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 --mkfsoptions "recordsize=1024K"
. The syntax of string needs some explanation.
The mkfs.lustre
command takes the string provided as an argument to --mkfsoptions
, prefixes the string with -o
and inserts it into the zfs
command line that creates the dataset. This can be observed in the output of the mkfs.lustre
command.
If only one property is being altered, then just create the <name>=<value>
pair string without any additional flags or arguments. However, if more than one property needs to be set, then separate each property with -o
. For example:
--mkfsoptions="recordsize=1024K -o mountpoint=none"
Refer to ZFS recordsize Property for recommendations on how to set the recordsize appropriately.
The --failnode
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 mkfs.lustre
command, it is not possible to set or change some properties of the zpool or its vdevs, such as the ashift
property. For this reason, it is highly recommended that the zpools be created independently of the mkfs.lustre
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 mkfs.lustre
to create the actual file system dataset inside the zpool:
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>
For example:
# 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
The output from the above example will look something like this:
# 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
Starting the OSS Service
The mount
command is used to start all Lustre storage services, including the OSS. The syntax is:
mount -t lustre [-o <options>] \ <ldiskfs blockdev>|<zpool>/<dataset> <mount point>
The mount
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 /dev/sda
or /dev/mapper/mpatha
, whereas for ZFS, the path resolves to a dataset in a zpool, e.g. demo-mdt0pool/mdt0
.
The mount point directory must exist before the mount command is executed. The recommended convention for the mount point of the OST storage is /lustre/<fsname>/ost<n>
, where <fsname>
is the name of the file system and <n>
is the index number of the OST.
The following example starts a ZFS-based OSS:
[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
As with all Lustre storage targets, only the mount -t lustre
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 lctl dl
and review the running processes:
[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]
Stopping the OSS Service
To stop a Lustre service, umount the corresponding target:
umount <mount point>
The mount point must correspond to the mount point used with the mount -t lustre
command. For example:
[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 ~]#
The regular umount
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 zfs unmount
command to stop a Lustre service. Attempting to use zfs
commands to unmount a storage target that is mounted as part of an active Lustre service will return an error.