Guidelines for calculating the size of a volume

What the volume size depends on

NetApp recommends that you use a minimum of seven disks to create a volume. so the size of your smallest volume should be six times your disk capacity (because one disk is for parity). In the example at Required information to create a volume, the disk size was 72 GB. A volume created with six of these disks provided a volume size of 407.4 GB.

If your volume requires more than 407 GB, you need to calculate its size based on the types and sizes of the storage units you intend to create on the volume. The storage units might be any of the following:

LUNs
Snapshots
Writable snapshots of LUNs (or backing store LUNs)
A backing store LUN means some or all of the unchanged data in the LUN is stored in the snapshot that was used to create the LUN.
LUN clones

Use the following table to determine the size of the volume that will contain the storage units you want to store in that volume.

If you create a LUN and...	Create a volume that...	Example (given that LUN = x bytes)
Do not use snapshots	Is at least 10% larger than the total size of the LUN (or the cumulative total of all the LUNs to be stored in the volume).	Volume size = x + 10%x or volume size = 1.10x. If LUN size = 10 GB, volume size = 1.10*10 GB or 11 GB
Take one or more snapshots	Is at least two times the size of the LUN, plus delta. Delta is the rate of change, given as a percentage.	Volume size = 2x delta. If LUN size = 10 GB, and the rate of change since the snapshot is 15%, volume size = 210 GB+(.1510 GB) = 21.5 GB. The first snapshot requires enough space to overwrite every block of data in the active file system; however, subsequent snapshots only require enough space to store what is overwritten in snapshot data. They do not require additional reserved space.
Create a backing store LUN using the `lun create -b` command	Has enough space to contain a backing store LUN, which is typically used for prototyping. This type of LUN only needs space for changed data, because the unchanged data it contains is stored in the snapshot from which it was created. You can create a backing store LUN with or without space reservation enabled, and you can create it as read-only, if desired.	With space reservation enabled (NOT using the `-o noreserve` option): volume size = original LUN size, plus snapshot requirements, plus space for this new LUN and its snapshot requirements. With space reservation disabled (using the `-o noreserve` option): Volume size = original LUN size, plus snapshot requirements.
Do a single file snap restore	Has enough space to store the original LUN and the restored LUN.	Volume size = 2x + 10%x or volume size = 2.1x.
Create a clone of the backing store LUN using the `lun clone` command	Has enough space to store the original LUN and its snapshot, and the LUN clone and its snapshot. To clone a backing store LUN and make it readable-writable, enable space reservations on the LUN and treat it as you would any other LUN.	Volume size = original LUN size, plus its snapshot requirements, plus the LUN clone and its snapshot requirements. Typically, this is 4x + delta.

Creating a volume using the command line

To use the command line to create a volume, complete the following step.

Step	Action
1	On the filer's command line, enter the following command: vol create volname disk-list volname is the name of the new volume (include the /vol/ prefix). disk-list is one of the following: ndisks [@disk-size] ndisks is the number of disks to use. It must be at least 2. disk-size is the disk size to use, in gigabytes. You must have at least two available disks of the size you specify. -d disk_name1 disk_name2... disk_nameN disk_name1, disk_name2... and disk_nameN are disk IDs of one or more available disks. Separate multiple disks with a space. Example `vol create vol1 8` For more information about the `vol` command, see the Storage Management Guide.

Step

Action

On the filer's command line, enter the following command:

vol create volname disk-list

volname is the name of the new volume (include the /vol/ prefix).

disk-list is one of the following:

ndisks [@disk-size]
ndisks is the number of disks to use. It must be at least 2.

disk-size is the disk size to use, in gigabytes. You must have at least two available disks of the size you specify.
-d disk_name1 disk_name2... disk_nameN
disk_name1, disk_name2... and disk_nameN are disk IDs of one or more available disks. Separate multiple disks with a space.

Example

vol create vol1 8

For more information about the vol command, see the Storage Management Guide.

Creating a volume using FilerView

To use FilerView to create a volume, complete the following steps.

Step	Action
1	Launch FilerView, as described in Launching FilerView.
2	In the left panel, click Volumes.
3	Click Add. Result The Volume Wizard appears. If you do not have enough disks, you see a message at the top of the Wizard. For example, if you only have one spare disk, you see the following message: The number of spares is 1. At least two spares must exist to create a new volume. Add enough disks to the filer to create a new volume.
4	Fill in the fields.
5	Click the Add button.

Organizing LUNs by creating qtrees using the command line

You can use qtrees to organize related LUNs into groups. To use the command line to create a qtree on the filer to host multiple LUNs, complete the following step.

Step	Action
1	On the filer's command line, enter the following command: qtree create /vol/volname/qtree-name Note Create the qtree in any volume other than the root volume (/vol/vol0). Include /vol in the path because if it does not begin with a slash (/), the qtree is created in the root volume. Example `qtree create /vol/vol1/qtree1` Result qtree1 is a qtree in /vol/vol1.

Step

Action

On the filer's command line, enter the following command:

qtree create /vol/volname/qtree-name

Note
Create the qtree in any volume other than the root volume (/vol/vol0). Include /vol in the path because if it does not begin with a slash (/), the qtree is created in the root volume.

Example

qtree create /vol/vol1/qtree1

Result

qtree1 is a qtree in /vol/vol1.

Organizing LUNs by creating qtrees using FilerView

To use FilerView to create a qtree in a volume, complete the following steps.

Step	Action
1	Launch FilerView, as described in Launching FilerView.
2	In the left panel, click Volumes > Manage > Qtrees > Manage > Add Qtree button.
3	Fill in the fields.
4	Click the Add button.