disksetup

The disksetup command formats specified disks for use by MapR storage and adds those disks to the disktab file.

You do not need to set up RAID (Redundant Array of Independent Disks) on disks used by MapR-FS. MapR uses disksetup to set up storage pools. In most cases, you should let MapR 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.

Syntax

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

Options

Option	Description
`-F`	Forces formatting of all specified disks. Disks that are already formatted for MapR 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 `disktab` contents from input disk list, but does not format disks. This option is useful if disk names change after a reboot, or if the `disktab` file is damaged.
`-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 MapR.

Specifying disks

The disksetup script is used to format disks for use by the MapR cluster. Create a text file /tmp/disks.txt listing the disks and partitions for use by MapR 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 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

NOTE:

The script disksetup removes all data from the specified disks. Make sure you specify the disks correctly, and that any data you wish to keep has been backed up elsewhere.

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 running


                  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

Then, you would add the following to the disk list file /tmp/disks.txt to be used by disksetup:

/root/storagefile