Truenas as a backup system - RAIDZ1 only

[Craig Curtin]

Guys,

Presently my main storage server is run on Centos 8 using Webmin and commandline utilities to serve up about 40TB of disk space in a RAID6 config. I am evaluating moving from this to Truenas.

As a way of putting my toe in the water with Truenas - i have a secondary system - the sole job of this system is to provide a backup of media from the main storage box - so currently this box is woken up every day through a cron job on the main system and WOL.

Once it is up and running it runs a script using RSYNC to replicate any changes from the live media system to local storage on this box.

As this is ONLY a backup box (we also send photos and home videos etc off-site) i use RAID 5 disks on this system - my practice in the past has been to purchase newer disks for the live storage system and then migrate the oldest disks from the live system to the backup system as additional storage is required.

I have up until now use LVM and RAID5 on this system with XFS on the actual partitions that are presented.

I think i have my head around the ZFS terminology etc so would assume that when i built this box with TrueNas i would set the drives up as RAIDZ1 ?

Does everything HAVE to be ZFS or are there other filesystem options ?

As the drives are different sizes (i have for instance at the moment 8 x 4TB WD Red, 4 x 6TB WD RED and 6 x 3TB WD ReD) on the system (i use multiple LSI controllers flashed into IT mode) would i just create a pool on each of the like sized drives and then add the drives to them ? If so is there the ability to "span" pools as LVM enables me to do on Linux and present all the storage as one entity ?

If i retire another 6TB drive (which will be coming up on the main server) - is it a simple task (or even possible) to add this into the pool with the other 6TB drives and expand the storage or do i have to blow away that pool and start again ?

thanks for the help

Craig

 

[Heffy]

@Craig Curtin I wouldn't be using older drives in RAIDZ1 because as I understand it, losing one drive will kill the entire backup. Personally I would consider RAIDZ2 as long as the redundancy doesn't cost you too much disk real estate.

FreeNAS - TrueNAS is really designed to be run 24/7, but having said that I have read that several people use their systems as on/off backup systems without much issue.

You can mix and match drive sizes, but each vdev's storage is limited to the smallest capacity drive. Currently I have 1 - 3Tb and 4 - 4Tb drive on one vdev which gives me about 7.5Tb of storage which will go to 10Tb when the 3 Tb drive is replaced.

Whether you can back up across vdev's is a question for someone else here with more experience.

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MOBO: ASUS M5A78L-M/USB3 AM3+ AMD 760G + SB710 USB 3.0
CPU: AMD FX-8320E Eight-Core Processor (3214.50 MHz K8-class)
RAM: 2-8Gb Crucial Ballistix DDR3 1600 UDIMM Memory
PSU: ???
NIC: Intel 82576 Gigabit
BOOT: 240Gb PNY SSD boot drive
DRIVES: 1-3Tb & 4-4Tb WD-Red CMR NAS Hard Drives Configured as RAIDZ2
CASE: Compaq mid size 6 bay case
TrueNAS Core 12.0 U1
FreeBSD 12.2-RELEASE-p2

 

[Craig Curtin]

@Craig Curtin I wouldn't be using older drives in RAIDZ1 because as I understand it, losing one drive will kill the entire backup. Personally I would consider RAIDZ2 as long as the redundancy doesn't cost you too much disk real estate.

FreeNAS - TrueNAS is really designed to be run 24/7, but having said that I have read that several people use their systems as on/off backup systems without much issue.

You can mix and match drive sizes, but each vdev's storage is limited to the smallest capacity drive. Currently I have 1 - 3Tb and 4 - 4Tb drive on one vdev which gives me about 7.5Tb of storage which will go to 10Tb when the 3 Tb drive is replaced.

Whether you can back up across vdev's is a question for someone else here with more experience.


Thanks for the response - RAID5 (or equivalent) is enough for me for the way this system is used - it is purely a convenience thing in that it is there to save me having to download 40TB of Shows and movies in the event of a massive system failure on the live box.

My understanding (correct me if i am wrong) is that i have single drive redundancy with RAIDZ1 i..e i can lose a drive and the array will continue to run in degraded mode until i add in a new drive - yes i know all about write errors and multiple drive failures etc.

Can i add another drive to an already established pool ? i.e. if i retire another drive from the production box and bring it across (lets say a 6TB drive) can i add it to the pool with the other 6TB drives - or do i have to recreate that pool ?

Craig

 

[sretalla]

My understanding (correct me if i am wrong) is that i have single drive redundancy with RAIDZ1 i..e i can lose a drive and the array will continue to run in degraded mode until i add in a new drive - yes i know all about write errors and multiple drive failures etc.

Correct.

Can i add another drive to an already established pool ? i.e. if i retire another drive from the production box and bring it across (lets say a 6TB drive) can i add it to the pool with the other 6TB drives - or do i have to recreate that pool ?

It's not currently possible to "expand" a RAIDZ VDEV/Pool to a different number of disks.
That feature is in development in OpenZFS, but is probably at least 12-24 months away from being present in TrueNAS (and may never arrive in FreeNAS).
Recreating the pool would be the currently available way to get the result.

 

[blanchet]

You can create a pool with the following layout

• 6 x 4 TB raidz2
• 6 x 4 TB raidz2 (use the 4 x 6TB to compensate for the missing 4 TB disk)
• 6 x 3 TB raidz2

At the beginning, it will provide 44 TB of space. (ZFS can use inline compression, so you may store more data)

• When you have two new 6TB disks, put them in the 2nd vdev
• When you have new 4 TB disks, put them in the 3rd vdev

When you replace the last smallest disk of a vdev, the pool space grows.