Creating a Volume
VERITAS Volume Manager uses logical volumes to organize and manage disk space. A volume is made up of portions of one or more physical disks, so it does not have the limitations of a physical disk.
For databases where the data storage needs to be resilient and the data layout needs to be optimized for maximum performance, we recommend using VxVM. The striping and mirroring capabilities offered by a volume manager will help you achieve your manageability, availability, and performance goals.
After you decide on a volume layout, you can use the vxassist command or the GUI to create the volume.
If you choose to use the GUI, the VERITAS Volume Manager Administrator's Guide provides a detailed comparison of the layout choices and more detailed procedures on creating each volume layout type. The GUI gives you the option of placing a file system on the new volume or mirroring during volume creation.
Usage Notes
- Creating a volume requires a disk group name, volume name, volume size, and volume layout. You will also need to know subdisk names if you are creating a striped volume.
- Striped or mirrored volumes require at least two disks.
- Striped pro and concatenated pro volumes are mirrored by default, so a striped pro volume requires more disks than an unmirrored striped volume and a concatenated pro volume requires more disks than an unmirrored concatenated volume.
- You cannot use a striped pro or concatenated pro volume for a root or swap volume.
- A RAID-5 volume requires at least three disks. If RAID-5 logging is enabled, a RAID-5 volume requires at least four disks.
- RAID-5 mirroring is not supported.
To create a volume using the command line
Use the vxassist command as follows:
# /opt/VRTS/bin/vxassist -g disk_group make volume_name size \
layout=layout_type
Example
To create a 1 GB mirrored volume called db01 on the PRODdg disk group:
# /opt/VRTS/bin/vxassist -g PRODdg make db01 1g layout=mirror
To create a volume using the GUI
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Under Disk Groups under the selected host in the left pane, click on the disk group to be used to create the volume.
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Choose Actions > New Volume. You are asked if you want Volume Manager to select the disks to use or if you want to select them manually.
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Select Manually select disks to use with this volume, then click Next.
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The Select Disks to use for Volume screen appears. You can now:
- Select disks to be used by VxVM when creating the volume. (Move to the Included: area.)
- Select disks not to be used by VxVM when creating the volume. (Move to Excluded: area.)
- Specify that the volume is to be mirrored across (Mirror Across:) or striped across (Stripe Across:) controllers, trays, targets, or enclosures.
Note
For ISP volumes, the layouts Mirror Across: and Stripe Across: cannot be specified.
- Specify ordered allocation (Ordered). Ordered allocation uses the specified storage to first concatenate disks, then to form columns, and finally to form mirrors.
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Click Next. The Select the attributes for this volume screen appears.
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Type in the Volume Name. This is a Volume Manager-specific name that is used in some Volume Manager commands. It is different from the volume label for the file system.
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Specify the volume size, or select Maxsize.
As you have already selected a disk, a size is shown in the volume size box that represents the maximum concatenated (simple or spanned) volume size on the disk. If you then click the Maxsize button, a new number appears in the volume size box that represents the maximum size for a spanned volume that spans all the disks in the group. You can also click on another volume layout and then click the Maxsize button to get the maximum size for that layout that involves unallocated space on all disks in the group.
If you choose Striped or RAID-5, Number of Columns and Stripe Unit Size need to have an entry. Defaults are provided.
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Select the required layout:
- Concatenated (Concatenated and Concatenated Mirrored)
- Striped (Striped and Striped Mirrored)
- RAID-5
- Mirrored
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Select the required options
Option
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Notes
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Mirror Info:
| - To mirror the volume, select Mirrored. In the Total Number of Mirrors field, enter the total number of mirrors for the volume.
Note Concatenated mirrored volumes are mirrored by default.
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Initialize zero:
| - To clear the volume before enabling it for general use, select Initialize Zero.
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No layered volumes:
| - To prevent the creation of a layered volume, select No Layered Volumes. In cases where a layered volume layout is appropriate, VxVM can create a layered volume when a non-layered layout is specified. This option ensures that the volume has a non-layered layout. If a layered (Pro) layout is selected, this option is ignored.
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Enable FastResync
Enable logging
| - If Enable FastResync is checked, then Enable Logging is an option only if the volume is mirrored.
- (The reason it is only enabled when Enable FastResync is checked is to ensure that a new style DRL is created.)
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After you provide all the necessary information in the dialog box, click Next. You are now asked if you want to create a file system.
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If you want to create a file system, select Create a File System and follow the instructions. If you do not want to create a file system, select No File System, then click Next.
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A summary of your selections appears. Click Back to make changes; otherwise, click Finish.
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