ZFS Pool creation

[eshrath]

Hello,

I am quite new to TrueNas and setting up the ZFS pool. Here is my the list of hard drives I have.

1) A pair of 150 GB hard drive.
2) A pair of 1 TB Hard drive.
3) One 5 TB Hard drive.

I am planning to create three pools of ZFS with one mirror for 150 GB pair, one mirror for 1 TB pair and Raid0 for 5 TB hard drive.

I am looking at using the storage for storing documents, pictures, media, videos etc.. and planning to keep the data in pool based on whether they need redundancy or not.

In few months, I might add one more 5 TB hard drive and make the 3rd pool a mirror and might look at changing all drive to 5TB for advance RaidZ2 or RaidZ3 configuration in the future.

Let me know if you its possible to create 3 pools in TrueNas in this config and any advantages and disadvantages of this configuration.

-Esh.

 

[sretalla]

might look at changing all drive to 5TB for advance RaidZ2 or RaidZ3 configuration in the future.

Everything you mentioned is fine except for this... changing pool topology is only possible for stripe to mirror and back, RAIDZ topology can't change once set, so if you want to go from mirror to RAIDZ, you need to have a separate pool and copy the data to it.

 

[Etorix]

I am planning to create three pools of ZFS with one mirror for 150 GB pair, one mirror for 1 TB pair and Raid0 for 5 TB hard drive.

You can have as many pools as you like. Please also note that a pool can have as many vdevs as you want.
So, to the extent that 150 GB HDD are of any use, you could have a redundant pool with 2*150 GB + 2*1 TB.

Do not mix the single 5 TB drive with anything else, as doing so would compromise the whole pool.

 

[eshrath]

You can have as many pools as you like. Please also note that a pool can have as many vdevs as you want.
So, to the extent that 150 GB HDD are of any use, you could have a redundant pool with 2*150 GB + 2*1 TB.

Do not mix the single 5 TB drive with anything else, as doing so would compromise the whole pool.

Etorix,

Thanks for your reply

Why would a 5TB pool comprise the whole pool? Is it because of the huge different in storage between 5TB drive the other smaller storage? (1 TB or 150 GB)?

 

[eshrath]

Everything you mentioned is fine except for this... changing pool topology is only possible for stripe to mirror and back, RAIDZ topology can't change once set, so if you want to go from mirror to RAIDZ, you need to have a separate pool and copy the data to it.

Sretalla,

Thanks for taking time to reply to my queries.

When I moved from Raid 0 or Mirror to Raidzn, I am ok to copy the data.

 

[eshrath]

Additionally, if I lose one of the mirror drive, do I lose the entire pool?

 

[sretalla]

Additionally, if I lose one of the mirror drive, do I lose the entire pool?

No, the loss of one member in a mirrored pair isn't catastrophic (although it does leave you ready for pool loss if the remaining disk dies before you can replace the lost one).

 

[Etorix]

Why would a 5TB pool comprise the whole pool? Is it because of the huge different in storage between 5TB drive the other smaller storage? (1 TB or 150 GB)?

A single drive vdev has no redundancy—which kinda defeats any reason to use ZFS in the first place.
Pool data is spread across all vdevs. If a pool comprises a single drive vdev, and this particular drive fails, then the whole pool is lost. Never use a single drive as a data vdev.