Partitioning Configuration

Partitioning Configuration

Use a spreadsheet. Don't make me come over there.

Why Stacki Uses Spreadsheets

Like a storage controller config, partitioning config done in a spreadsheet is a Stacki best practice. You can see it, play with it, and validate your partition config when it's loaded.

Please note: Partitioning is done in parallel. Stacki is the only installer that does this.

Spreadsheet

The configuration of disk partitions can be specified in a spreadsheet with the following columns:

1. Name. A host name, appliance type or 'global'.
2. Device. The Linux disk device name (e.g., sda, sdb).
3. Mountpoint. Where the partition should be mounted on the file system.
4. Size. The size of the partition in megabytes. '0' will instruct the installer to use the remaining available space of the device.
5. Type. How the partition should be formatted (e.g., xfs, swap).
6. Options. Free form string of options that can be used to create a partition.

An example spreadsheet is shown below.

Note: Example spreadsheets for partitioning configuration are also available on your frontend in /opt/stack/share/examples/spreadsheets. Look for files with 'partition' in the name.

Name	Device	Mountpoint	Size	Type	Options
global	sda	biosboot	1	biosboot
	sda	/	50000	ext4
	sda	/var	80000	ext4
	sda	swap	16000	swap
	sda	/scratch	0	xfs
backend	sda	biosboot	1	biosboot
	sda	/	50000	ext4
	sda	/var	10000	ext4
	sda	swap	16000	swap
	sda	/scratch	1	xfs	--grow --maxsize=4000
	sdb	/hadoop01	0	xfs
	sdc	/hadoop02	0	xfs
backend-0-1	sda	biosboot	1	biosboot
	sda	/	10000	ext4
	sda	swap	1000	swap
	sdb	pv.01	8000	lvm
	pv.01	volgrp01	6000	volgroup
	volgrp01	/extra	4000	ext4	--name=extra

The Name column can contain a specific host name (e.g., backend-0-0), an Appliance type (e.g., backend) or it can be set to global.

In the sample spreadsheet, we see the default configuration (global) is to only configure the partitions for the first disk (sda). The root partition / is an ext4 partition and it is 50 GB. The /var partition is an ext4 partition and it is 80 GB. The swap partition is 16 GB. Lastly, /scratch is an xfs partition and it will be the remainder of sda.

The default configuration for all backends, backend, has a similar configuration for sda as the global configuration except for the /scratch partition. The maximum size of /scratch partition is set to 1 GB via the Options column. Additionally, sdb and sdc will be configured for all backends as single partitions that span the entire disk.

Note: a "biosboot" partition must exist for any system disk on a CentOS/RHEL 7.x system. Make sure you define this.

LVM

Stacki supports specifying LVM configuration via a spreadsheet. lvm, volgroup are keywords that indicate that the partition needs to be setup via LVM. In the configuration for backend-0-1, pv.01 is configured as a physical volume on sdb with size as 8GB. volgrp01 is a volgroup comprising of pv.01. /extra is mounted as an lvm partition on volgroup volgrp01.

Raid

Software raid can also be defined easily in a partition file. Do this instead of the dumb software RAID defined in the hardware BIOS your equally cheap and dumb white box or bottom of the line A-list vendor box came with.

NAME	DEVICE	MOUNTPOINT	SIZE	TYPE	OPTIONS
backend	md0	/	0	ext4	--level=RAID1 raid.01 raid.02
	md1	/boot	200	ext4	--level=RAID1 raid.03 raid.04
	md2	/tmp	3192	ext4	--level=RAID1 raid.05 raid.06
	md3	/var	20480	ext4	--level=RAID1 raid.07 raid.08
	md4	/var/log	1024	ext4	--level=RAID1 raid.09 raid.10
	md5	/var/log/audit	20480	ext4	--level=RAID1 raid.11 raid.12
	sda	biosboot	1	biosboot
	sdb	biosboot	1	biosboot
	sda	swap	8192	swap
	sdb	swap	8192	swap
	sda	raid.01	0	raid
	sdb	raid.02	0	raid
	sda	raid.03	200	raid
	sdb	raid.04	200	raid
	sda	raid.05	3192	raid
	sdb	raid.06	3192	raid
	sda	raid.07	20480	raid
	sdb	raid.08	20480	raid
	sda	raid.09	1024	raid
	sdb	raid.10	1024	raid
	sda	raid.11	20480	raid
	sdb	raid.12	20480	raid

Note: The 'biosboot' partition on both of the physical drives.

When you are finished editing your spreadsheet, save it as a CSV file, then copy the CSV file to your frontend.

Then, load the CSV file into the database on the frontend by executing:

# stack load storage partition file=partition.csv

You can view your storage partition configuration by executing:

# stack list storage partition

The nukedisks Attribute

A host's disk partitions will only be reconfigured if the nukedisks attribute is set to true. On first install, all installing backend disks automatically have nukedisks set to false. If you've added backend nodes via spreadsheet, you must set nukedisks to true as in the example below, before installing.

As an example, to set the nukedisks attribute for host backend-0-0, execute:

# stack set host attr backend-0-0 attr=nukedisks value=true

For all hosts:

# stack set host attr a:backend attr=nukedisks value=true

Then, the next time backend-0-0 is installed, it will remove all partitions for all disks, then repartition the disks as you specified in your spreadsheet.

While a host is installing, after it partitions its disks, it will send a message to the frontend to instruct it to set the nukedisks attribute back to false.

This ensures that the disks will not be reconfigured on the next installation.

Its benefit is less obvious if you're using "xfs" but it's very obvious if you're still using "ext4." (Why are you still using ext4?)