| Oracle® VM Server User's Guide Release 2.2 Part Number E15444-04 |
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PDF · Mobi · ePub |
| Oracle® VM Server User's Guide Release 2.2 Part Number E15444-04 |
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PDF · Mobi · ePub |
Oracle VM uses the concept of storage repositories to define where Oracle VM resources may reside in a server pool. Resources include guest virtual machines, virtual machines templates (guest seed images), ISO images, shared virtual disks, and so on.
A storage repository is required for High Availability (HA) fail over, and for live migration of domains.
A storage repository should be set up using external storage based on any of the following technologies:
OCFS2 (Oracle Cluster File System) using the iSCSI (Internet SCSI) network protocol
OCFS2 using SAN (Storage Area Network)
NFS (Network File System)
To enable HA or live migration, you must make sure all Oracle VM Servers:
Use the same storage repository
Are in the same server pool
If you used the default /OVS partition during installation, and you have only one Oracle VM Server in your server pool, you do not need to create a storage repository. If you want to add more Oracle VM Servers to your server pool, you must create a storage repository and remove the local /OVS partition created during installation.
If you have only one Oracle VM Server in your server pool, but want to use iSCSI, SAN or NFS-based storage for your guest domains, you must create a storage repository, even though it will not be shared.
You prepare the external storage and storage repository at the Oracle VM Server command line, and then use Oracle VM Manager to create a server pool, and propagate the storage repository to all Oracle VM Servers in the server pool.
You can also manage the HA of server pools and guests, and live migration of domains, using Oracle VM Manager. See the Oracle VM Manager User's Guide for more information.
This Chapter discusses preparing external storage, and storage repositories to be used in Oracle VM Manager to create server pools, and contains:
If you want to enable HA, or perform live migration of domains to other, identical, computers, you must first create external storage, and then create a storage repository to be used in the server pool.
When you create a server pool in Oracle VM Manager, the external storage is automatically mounted on each Oracle VM Server in the server pool (the cluster). Similarly, when an Oracle VM Server in the server pool is restarted, the external storage is automatically mounted. Make sure the external storage is available to the Oracle VM Servers in the server pool so it can be automatically mounted when an Oracle VM Server is restarted.
This section discusses:
When you have prepared the external storage, prepare the storage repository. See Section 8.2, "Preparing a Storage Repository" for information on preparing a storage repository.
To prepare external storage to be used in a storage repository using OCFS2 on iSCSI:
Start the iSCSI service:
# service iscsi start
Run discovery on the iSCSI target. In this example, the target is 10.1.1.1:
# iscsiadm -m discovery -t sendtargets -p 10.1.1.1
This command returns output similar to:
10.1.1.1:3260,5 iqn.1992-04.com.emc:cx.apm00070202838.a2 10.1.1.1:3260,6 iqn.1992-04.com.emc:cx.apm00070202838.a3 10.2.1.250:3260,4 iqn.1992-04.com.emc:cx.apm00070202838.b1 10.1.0.249:3260,1 iqn.1992-04.com.emc:cx.apm00070202838.a0 10.1.1.249:3260,2 iqn.1992-04.com.emc:cx.apm00070202838.a1 10.2.0.250:3260,3 iqn.1992-04.com.emc:cx.apm00070202838.b0
Delete entries that you do not want to use, for example:
# iscsiadm -m node -p 10.2.0.250:3260,3 -T iqn.1992-04.com.emc:cx.apm00070202838.b0 -o delete # iscsiadm -m node -p 10.1.0.249:3260,1 -T iqn.1992-04.com.emc:cx.apm00070202838.a0 -o delete # iscsiadm -m node -p 10.2.1.250:3260,4 -T iqn.1992-04.com.emc:cx.apm00070202838.b1 -o delete # iscsiadm -m node -p 10.1.1.249:3260,2 -T iqn.1992-04.com.emc:cx.apm00070202838.a1 -o delete # iscsiadm -m node -p 10.0.1.249:3260,5 -T iqn.1992-04.com.emc:cx.apm00070202838.a2 -o delete
Verify that only the iSCSI targets you want to use for the server pool are visible:
# iscsiadm -m node
Review the partitions by checking /proc/partitions:
# cat /proc/partitions major minor #blocks name 8 0 71687372 sda 8 1 104391 sda1 8 2 71577607 sda2 253 0 70516736 dm-0 253 1 1048576 dm-1
Restart the iSCSI service:
# service iscsi restart
Review the partitions by checking /proc/partitions. A new device is listed.
# cat /proc/partitions major minor #blocks name 8 0 71687372 sda 8 1 104391 sda1 8 2 71577607 sda2 253 0 70516736 dm-0 253 1 1048576 dm-1 8 16 1048576 sdb
The new device can now be used. Use the fdisk utility to create at least one partition:
# fdisk /dev/sdb
Alternatively, if the external storage is more than 2 TB, use the gparted utility to create a BIOS boot partition (GPT):
# gparted /dev/sdb
Format the partition from any of the Oracle VM Servers in the (intended) server pool with a command similar to the following:
# mkfs.ocfs2 -Tdatafiles -N8 /dev/sdb1
The -Tdatafiles parameter makes mkfs.ocfs2 use a large cluster size. The size chosen depends on the device size.
Add an additional parameter, --fs-features=local, if you are not mounting the volume in the server pool (cluster).
The -N8 parameter allocates 8 slots to allow that many nodes to mount the file system concurrently. Increase the number if the server pool has (or will have) greater than 8 nodes. It is recommended that you have at least 8 slots, even for a local file system. Creating slots for a local file system allows users to easily cluster-enable the shared volume later.
For more information on using OCFS2, see the OCFS2 documentation online at:
http://oss.oracle.com/projects/ocfs2/documentation/v1.4/
http://oss.oracle.com/projects/ocfs2-tools/documentation/v1.4/
When you have prepared the external storage, prepare the storage repository. See Section 8.2, "Preparing a Storage Repository" for information on preparing a storage repository.
To prepare external storage to be used in a storage repository using OCFS2 on SAN:
Review the partitions by checking /proc/partitions:
# cat /proc/partitions major minor #blocks name 8 0 71687372 sda 8 1 104391 sda1 8 2 71577607 sda2 253 0 70516736 dm-0 253 1 1048576 dm-1 8 16 1048576 sdb
Determine the share disk volume you want to use. You may need to use the fdisk utility to create at least one partition on the shared disk volume:
# fdisk /dev/sdb
Alternatively, if the external storage is more than 2 TB, use the gparted utility to create a GPT partition:
# gparted /dev/sdb
Format the partition from any of the Oracle VM Servers in the (intended) server pool with a command similar to the following:
# mkfs.ocfs2 -Tdatafiles -N8 /dev/sdb1
The -Tdatafiles parameter makes mkfs.ocfs2 use a large cluster size. The size chosen depends on the device size.
Add an additional parameter, --fs-features=local, if you are not mounting the volume in the server pool.
The -N8 parameter allocates 8 slots to allow that many nodes to mount the file system concurrently. Increase the number if the server pool has (or will have) greater than 8 nodes. It is recommended that you have at least 8 slots, even for a local file system. Creating slots for a local file system allows users to easily cluster-enable the shared volume later.
For more information on using OCFS2, see the OCFS2 documentation online at:
http://oss.oracle.com/projects/ocfs2/documentation/v1.4/
http://oss.oracle.com/projects/ocfs2-tools/documentation/v1.4/
When you have prepared the external storage, prepare the storage repository. See Section 8.2, "Preparing a Storage Repository" for information preparing a storage repository.
To prepare external storage to be used in a storage repository using NFS, find an NFS mount point to use. This example uses the mount point:
mynfsserver:/vol/vol1/data/ovs
When you have identified an NFS mount point to use for the external storage, prepare the storage repository. See Section 8.2, "Preparing a Storage Repository" for information on preparing a storage repository.
In addition to preparing external storage for a server pool, you must also prepare a storage repository. The storage repository is used to host the resources used in the server pool, such as guest virtual machines and shared virtual disks.
The storage repository is used by Oracle VM Manager when you create a server pool and is automatically propagated to all Virtual Machine Servers in the server pool.
Creating a server pool ensures the safety of guest data, and protects from runaway nodes which may become unreachable. Oracle VM Servers in a server pool are in a cluster and have built-in rules and restrictions which are more stringent than unclustered Oracle VM Servers, for example, Quorum is needed and may require restarting one or more Oracle VM Servers to preserve the cluster under rare circumstances.
You can create a server pool using NFS- or OCFS2-based external storage. You must have at least one storage repository created and ready to use before you create a server pool. To prepare external storage for use in a storage repository, see Section 8.1, "Preparing External Storage".
Before you create a storage repository, make sure that every Oracle VM Server in the server pool has been correctly configured:
The host name in the /etc/hosts file is associated with the public IP address, and not with 127.0.0.1. To make sure the hostname is correctly set in the /etc/hosts file, ping the host name of all Oracle VM Servers in the server pool to display their public IP addresses.
You have all the Oracle VM Server entries in your DNS server. If you do not use DNS, make sure the correct setting is in the /etc/hosts file for all the Oracle VM Servers in the server pool. If you plan to use DNS for all Oracle VM Servers, but DNS was not specified during the Oracle VM Server installation, update the /etc/resolv.conf file and add your domain name to it.
All the Oracle VM Servers in the server pool must use consistent name resolution, either using a DNS server, or using the /etc/hosts file. You should not have mixed name services for the Oracle VM Servers a server pool. For example, some Oracle VM Servers use DNS, while others use the /etc/hosts file to resolve host names.
To prepare a storage repository for use in Oracle VM Manager when a server pool is created:
On the Server Pool Master, create a storage repository with the script:
/opt/ovs-agent-2.3/utils/repos.py -n storage_location
For example, for an NFS set up, you might use something similar to:
# /opt/ovs-agent-2.3/utils/repos.py -n mynfsserver:/vol/vol1/data/ovs
Or for an OCFS2 using iSCSI or SAN set up, you might use something similar to:
# /opt/ovs-agent-2.3/utils/repos.py -n /dev/sdb1
The repos.py -n command from the previous step displays the UUID of the storage repository you created. You need this UUID to set the cluster root. Copy the UUID for the storage repository you want to use as the cluster root.
Paste the UUID for the storage repository and use it to set the cluster root with the command:
# /opt/ovs-agent-2.3/utils/repos.py -r UUID
For more detailed information on using the repos.py script, see Section 9.2, "Managing Storage Repositories".
The external storage and storage repository are configured and ready to use.
Log in to Oracle VM Manager and create a server pool. The storage repository is automatically propagated and the external storage mounted on all Virtual Machine Servers in the server pool.
Note:
If you use Oracle VM Manager to create a server pool, you do not need to use therepos.py -i command to initialize the storage repository. Oracle VM Agent automatically mounts the shared storage on each Virtual Machine Server in the server pool.
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