Configuring TrueNAS - Create a Data-Pool

Posted on August 16, 2024 • 5 min read • 878 words

After TrueNAS itself has been installed, a data pool is first created, the layout of which has a significant influence on the performance of the network storage.

Configuring TrueNAS - Create a Data-Pool
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Serie TrueNAS

This is an article in the series TrueNAS - a NAS for your Homelab

Configuring TrueNAS

Various Data-Pool Layouts

TrueNAS is based internally on the ZFS file system, which is why the equivalent ZFS designations are often used in the context of TrueNAS (RAID 5 <-> RAID-Z1, RAID 6 <-> RAID-Z2). However, the idea of distributing data across different disks is the same.

Raid Level (1-VDEV) Pro Con Main Usage
RAID-0 Striping Usable capacity is the sum of all individual disk capacities, max. high read/write speed no redundancy Only use if data can be lost
RAID-1 Mirroring high read speed lower write speed, total number of disks need to be even, usable capacity max. 50% Use if max. concurrent read/write operationen and redundancy is needed
RAID-Z1 Stripping, 1 Parity 1 defect disk can be compensated, lower read/write speed increasing with number of disks Usable capacity (number of disks minus 1) * smallest single-disk-capacity Compromise between usable capacity/redundancy and speed
RAID-Z2 Stripping, 2 Parity 2 defect disks can be compensated, lower read/write speed increasing with number of disks Usable capacity (number of disks minus 2) * smallest single-disk-capacity Compromise between usable capacity/redundancy and speed
RAID-Z3 Stripping, 3 Parity 3 defect disks can be compensated, lower read/write speed increasing with number of disks Usable capacity (number of disks minus 3) * smallest single-disk-capacity Compromise between usable capacity/redundancy and speed
Summary of: iX systems whitepaper - ZFS STORAGE POOL LAYOUT

Notes on read/write speeds

  • A current rotating hard drive can read and write data at around 150 MB/s. Home networks are still often 1 GBit networks due to the cheap components, which can therefore move data at around 100 MB/s. In this context, it makes perfect sense to favour the higher usable capacity of a RAID-Z1 or RAID-Z2 over the higher speed of a RAID-1 layout.
  • For the same reason, a NAS consisting only of SSDs offers no advantages in terms of maximum transfer speed. However, it will show a noticeable advantage over rotating hard drives if a large number of small files are frequently moved.
  • Depending on the type of use of a NAS consisting of rotating hard disks, performance can be increased if an SSD ZFS L2ARC read cache is added to the system. (see below definition of the pool layout, optional cache)
  • If it is possible to use a larger number of hard disks (~ >10), the ZFS file system and therefore TrueNAS also offers the option of defining several VDEVs in parallel. This makes it possible to distribute read/write accesses even better in the system and thus significantly increase them. Multiple VDEVs are not discussed further in this article.

Create a Data-Pool

From TrueNAS main dashboard you can access the storage management area via -> Storage.


Click -> Storage -> Disks to display the list of hard disks recognised in the system. There should now be some disks here that are not yet assigned to a pool (N/A)


A new pool can be created using the Pool Creation Wizard (-> Storage -> Create Pool), which guides you step by step or section by section through the creation process.


In General Info section, enter a name for the pool to be created

  • Name: Test-Pool

The layout of the pool is defined in the Data section. At the beginning of this article, I summarised the advantages and disadvantages of a selection of layouts in a table. In this example, a RAID 5 / RAID-Z1 is to be created from all four disks, so one disk can completely fail and all data will remain available.

  • Layout: RAID-Z1
  • Disk Size: given 20GB
  • Width: 4
  • Number of VDEVs: is computed to 1, as all disks are already assigned

you can also assign disks manually

  • Layout: RAID-Z1

  • -> Manual Disk Selection


  • -> Add VDEV


  • The required hard disks can now be dragged and dropped into the VDEV.

The result is the same as with keyboard input


-> Save Selection

In the LOG (Optional) section, dedicated hard disks can be added as write cache

  • continue without cache

In the Spare (Optional) section, hard disks can be added that immediately take over in the event of the failure of another pool disk

  • continue without spare disc

In the Cache (Optional) section, dedicated hard disks can be added as ZFS L2ARC read-cache

  • continue without cache

In the section Metadata (Optional) dedicated hard disks can be added to accelerate the Meta Data and Block IO

  • continue without cache

In the section Dedup (Optional) dedicated hard disks for de-duplication tables can be added

  • continue without de-duplication VDEV

The Review section summarises the entries


-> Create Pool to create a pool

Confirm that the contents of all hard drives will be deleted -> Continue


The pool is then created


The pool has been created and the dashboard for this pool is displayed.


Conclusion

In Configuring TrueNAS - Create a Samba Share we’ll finally use the data pool to expose a Samba network share in our network.

References

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