disksetup

Describes the disksetup command that formats disks for use by HPE Ezmeral Data Fabric storage.

Description

NOTE The disksetup command must be run as root.

The disksetup command formats specified disks for use by HPE Ezmeral Data Fabric storage, and adds those disks to the disktab file.

You do not need to set up Redundant Array of Independent Disks (RAID) on disks used by the file system. HPE Ezmeral Data Fabric uses disksetup to set up storage pools. In most cases, you should let HPE Ezmeral Data Fabric calculate storage pools using the default stripe width of two or three disks. If you anticipate a high volume of random-access I/O, you can use the -W option to specify larger storage pools of up to 8 disks each.

See Setting Up Disks for MapR for more information about when and how to use disksetup.

IMPORTANT On RHEL 8.1, run the following command to symlink /usr/bin/python to /usr/bin/python3. The disksetup command fails if /usr/bin/python is not found.

sudo alternatives --set python /usr/bin/python3

Syntax

/opt/mapr/server/disksetup
    [-F]
    [-G]
    [-X]
    [-M]
    [-W <stripe_width>]
    <disk list file>

Options

Option	Description
`-F`	Forces formatting of all specified disks. Disks that are already formatted for HPE Ezmeral Data Fabric are not reformatted by `disksetup` unless you specify this option. The `-F` option fails when a filesystem has an entry in the `disktab` file, is mounted, or is in use. Call `maprcli disk remove` to remove a disk entry from the `disktab` file.
`-G`	Generates the `disktab` file contents from input disk list, but does not format disks. Use this option if the `disktab` file is completely lost, and you need to regenerate it based on an input list of disks assigned to MapR-FS. This option reads the GUID from the provided disks, and generates the `disktab` output to stdout. You can redirect the output to a file.
`-X`	Fixes `disktab` contents from `/proc/partitions`, but does not format disks. Use this option if there is a change in the names of the disk devices referenced by `disktab`, but the disks themselves are still usable. For example, if `/dev/sdb` has been renamed to `/dev/sdf` but the device itself has the same GUID, only the `disktab` contents need to be updated to point to `/dev/sdf`.
`-M`	Uses the maximum available number of disks per storage pool.
`-W`	Specifies the number of disks per storage pool.

Examples

Setting up disks specified in the file /tmp/disks.txt:

/opt/mapr/server/disksetup -F /tmp/disks.txt

Reformatting all disks

To reformat all disks, remove the disktab file and issue the disksetup -F command to format the disk:

/opt/mapr/server/disksetup -F

To reformat a particular disk from the disktab, use the maprcli disk remove and maprcli disk add commands. For more information, see Setting Up Disks for HPE Ezmeral Data Fabric.

Specifying disks

To specify the disks to be formatted for use by the HPE Ezmeral Data Fabric cluster, create a text file /tmp/disks.txt listing the disks and partitions for use by HPE Ezmeral Data Fabric on the node. Each line lists either a single disk, or all applicable partitions on a single disk. When listing multiple partitions on a line, separate each partition by spaces. For example:

/dev/sdb
/dev/sdc1 /dev/sdc2 /dev/sdc4
/dev/sdd

Later, when you run disksetup to format the disks, specify the disks.txt file. For example:

/opt/mapr/server/disksetup -F /tmp/disks.txt

IMPORTANT

The disksetup command removes all data from the specified disks. Ensure that you specify the disks correctly, and that you have backed up any data that you wish to keep.

If you are re-using a node that was used previously in another cluster, be sure to format the disks to remove any traces of data from the old cluster.

WARNING Run


               disksetup

only after you run the


               configure.sh

Test Purposes Only: Using a Flat File for Storage

When setting up a small cluster for evaluation purposes, if a particular node does not have physical disks or partitions available to dedicate to the cluster, you can use a flat file on an existing disk partition as the node's storage. Create at least a 16GB file, and include a path to the file in the disk list file for the disksetup script.

The following example creates a 20 GB flat file (bs=1G specifies 1 gigabyte blocks, multiplied by count=20) at /root/storagefile:

dd if=/dev/zero of=/root/storagefile bs=1G count=20

Next, add the following entry to the disk list file /tmp/disks.txt to be used by disksetup:

/root/storagefile