====== ZFS - Pools - Create a ZFS Pool - Comprehensive Steps to Create a ZFS Pool ======

===== Choose Drives to Pool =====

Check installed drives by running:

<code bash>
sudo fdisk -l
</code>

returns:

<code bash>
Disk /dev/sdb: 14.57 TiB, 16000900661248 bytes, 31251759104 sectors
Disk model: ST16000NM001G-2K
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes

Disk /dev/sdc: 14.57 TiB, 16000900661248 bytes, 31251759104 sectors
Disk model: ST16000NM001G-2K
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
</code>

<WRAP info>
**NOTE:**  Note down the device names of drives you want to pool.
</WRAP>

Another method to check the disks:

<code bash>
lsblk -S
</code>

returns:

<code bash>
NAME HCTL       TYPE VENDOR   MODEL                 REV TRAN
sdb  5:0:0:0    disk ATA      ST16000NM001G-2KK103 SN02 sata
sdc  8:0:0:0    disk ATA      ST16000NM001G-2KK103 SN02 sata
</code>

<WRAP important>
**WARNING:**  Ensure that the disk with the Ubuntu operating system is not used.

  * Also exclude any other disks that may contain data not to be destroyed.

</WRAP>

----

===== Delete Existing Partitions if required =====

Delete all partitions and reset it:

<code bash>
sudo sgdisk - -zap-all /dev/sdb
</code>


Create a partition with 1GB of trailing free space:

<code bash>
sudo sgdisk -n1:0:-1G -t1:BF00 /dev/sdb
</code>

<WRAP info>
**NOTE:**  Adjust these values as required.
</WRAP>


<WRAP info>
**NOTE:**  This will result in a /dev/sdb1 partition being created.
</WRAP>

----

===== Creating a Pool =====

Different types of storage pools can be created:

==== To create a striped pool ====

<code bash>
sudo zpool create testpool /dev/sdb /dev/sdc
</code>

<WRAP info>
**NOTE:**  This is equivalent to RAID0.

  * This has no parity and no mirroring to rebuild the data.
  * This is not recommended because of the risk of losing data if a drive fails.

</WRAP>

----

==== To create a mirrored pool ====

<code bash>
sudo zpool create testpool mirror /dev/sdb /dev/sdc
</code>

<WRAP info>
**NOTE:**  Much like RAID1, one can use 2 or more VDEVs.

  * For N VDEVs, one will have to have N-1 fail before data is lost.

</WRAP>

----

==== To create a Striped Mirrored VDEVs ====

<code bash>
sudo zpool create example mirror /dev/sdb /dev/sdc mirror /dev/sdd /dev/sde

or

sudo zpool create example mirror /dev/sdb /dev/sdc
sudo zpool add example mirror /dev/sdd /dev/sde
</code>

<WRAP info>
**NOTE:**  Much like RAID10.

  * Great for small random read I/O.
  * Create mirrored pairs and then stripe data over the mirrors.
  * This creates striped 2 x 2 mirrored pool.

</WRAP>

----

==== To create a RAIDZ pool ====

<code bash>
sudo zpool create testpool mirror /dev/sdb /dev/sdc
sudo zpool create example raidz /dev/sdb /dev/sdc /dev/sdd /dev/sde
</code>

<WRAP info>
**NOTE:**  Like RAID5.

  * This uses a variable width strip for parity.
  * Allows one to get the most capacity out of a bunch of disks with parity checking with a sacrifice to some performance.
  * Allows a single disk failure without losing data.

</WRAP>

----

==== To create a RAIDZ2 pool ====

<code bash>
sudo zpool create example raidz2 /dev/sdb /dev/sdc /dev/sdd /dev/sde /dev/sdf
</code>

<WRAP info>
**NOTE:**  Like RAID6.

  * Has double the parity for 2 disk failures with performance similar to RAIDZ. 

</WRAP>

----

==== To create a RAIDZ3 pool ====

<code bash>
sudo zpool create example raidz3 /dev/sdb /dev/sdc /dev/sdd /dev/sde /dev/sdf /dev/sdg
</code>

<WRAP info>
**NOTE:**  Better than RAID6.

  * Has 3 parity bits, allowing for 3 disk failures before losing data with performance like RAIDZ2 and RAIDZ.

</WRAP>

----

==== To create a Nested Raid pool ====

<code bash>
sudo zpool create example raidz /dev/sdb /dev/sdc /dev/sdd /dev/sde
sudo zpool add example raidz /dev/sdf /dev/sdg /dev/sdh /dev/sdi
</code>

<WRAP info>
**NOTE:**  Like RAID50, RAID60, striped RAIDZ volumes.

  * This is better performing than RAIDZ but at the cost of reducing capacity.

</WRAP>


----

<WRAP info>
**NOTE:**  Here, entire disks are being used for the pool.

  * ZFS also supports creating pools from disk partitions, such as /dev/sdb1.
  * Anything with a descriptor in /dev that allows random access will work.
    * Test pools made of sparse files are an incredibly convenient way to practice zpool commands.

</WRAP>

<WRAP info>
**NOTE:**  The newly mounted pool will appear as any other part of the filesystem.

  * **testpool** is the name of the pool.

  * The newly created pool will be mounted at **/testpool**.
    * You can select a different mount point using the **-m** option: <code bash>
sudo zpool create -m /mnt/testpool testpool mirror /dev/sdb /dev/sdc
</code>

</WRAP>

<WRAP info>
**NOTE:**  If any error appears, the command can be rerun with the **-f** option after the zpool create command which forces the command to be executed:

<code bash>
sudo zpool create -f testpool /dev/sdb /dev/sdd
</code>

</WRAP>


<WRAP info>
**NOTE:**  Advanced options can also be used when creating a pool.

<code bash>
sudo zpool create -f -o ashift=12 -O compression=lz4 my_pool /dev/sdb1
</code>

  * **ashift**:  corresponds to 4k sector size.
  * **compression**: Enables LZ4 compression.
  * **my_pool**:  The name of my new zpool.
  * **/dev/sdb1**:  The disk partition to use for the pool.

</WRAP>


----

===== List Mounts =====

Check the Mount is showing:

<code bash>
df -h
</code>

----

===== Set Permissions of the Mount =====

By default only root can write to the mounted directory.

Change this so that any ordinary user can make changes to the directory:

<code bash>	
sudo chown -Rfv peter:peter /testpool
</code>

----

===== Check Pool Status =====

<code bash>
sudo zpool status
</code>