confusion between double pool and raid

[trisonic]

hello

I'm a little confused as to what the optimal configuration might be on my machine:
I have a supermicro server with 14tb and I created a 7tb volume in raid10 using the integrated sas controller.

i understand that i should create a few gigs volume for the install truenas (boot-pool).
and the rest i could use for data.

but i don't understand why i should create two identical volumes (and then create a truenas pool made of two disks) if i have a raid10 at a lower level.

i was thinking to create 2 volumes at raid level:
one 32gb where i could install truenas (boot-pool)
and a single volume for data

from truenas create a single pool made of a single data disk (that would be the data volume of the hardware raid)...

...i'm a little bit confused...can you help me?

thanks

 

[Arwen]

Uh, hardware RAID, (aka RAID-10 in the integrated SAS controller), is not recommended for use with ZFS on TrueNAS.

TrueNAS is designed to handle the RAID, (Mirrored or RAID-Zx), using ZFS. By using a hardware RAID-10 some of ZFS features are not available. And depending on the exact model of hardware RAID controller, potentially something that can lead to data loss when using ZFS.

Further, the boot pool is purposefully designed to be separate from any data pools. This allows it to have zero redundancy and fail, without impacting any data pools. You can backup the configuration, which would allow full restoration of function. Or you can use ZFS mirrored boot pool devices to allow single boot device failures without impact.

See these posts:
What's all the noise about HBA's, and why can't I use a RAID controller?
Hardware Recommendations Guide Discussion Thread
Don't be afraid to be SAS-sy ... a primer on basic SAS and SATA

I was unable to find the ZFS intro, but you should read up on ZFS redundancy, scrubbing and error recovery. All of which are impacted when using a hardware RAID controller's LUN.

In essence, TrueNAS is designed with direct access to the disks in mind, allowing all the features to work. Including ZFS redundancy, scrubbing with repair and full error recovery, (to the level of redundancy you design into your data pool). Plus, SMART tests and warnings are available on the individual disks, which most hardware RAID controllers don't support.


To be clear, in production Data Centers, hardware RAID with ZFS is used all the time, (with Solaris 10 & 11). But, PCIe card type RAID controllers are not in the same league as EMC, Hitachi, and other Data Center SAN storage.

 

[trisonic]

Uh, hardware RAID, (aka RAID-10 in the integrated SAS controller), is not recommended for use with ZFS on TrueNAS.

ok now it's clearer to me!

i have a X9DRD-7LN4F-JBOD motherboard with broadcom 2308 integrated raid.

currently i have flashed the 2308 firmware in IR (Raid) mode and configured the disks in raid10.

can i flash the 2308 in IT mode without raid.... this should be the right mode for the purpose: let truenas manage the raid and see every single disk....
right!? :)

luckily i found a 32gb ssd, maybe i could put truenas on this ssd.


thanks

Translated with www.DeepL.com/Translator (free version)

To be clear, in production Data Centers, hardware RAID with ZFS is used all the time, (with Solaris 10 & 11). But, PCIe card type RAID controllers are not in the same league as EMC, Hitachi, and other Data Center SAN storage.

I didn't understand this point.
I understand that it is the exact opposite of the above :)

 

[Arwen]

ok now it's clearer to me!

i have a X9DRD-7LN4F-JBOD motherboard with broadcom 2308 integrated raid.

currently i have flashed the 2308 firmware in IR (Raid) mode and configured the disks in raid10.

can i flash the 2308 in IT mode without raid.... this should be the right mode for the purpose: let truenas manage the raid and see every single disk....
right!? :)

luckily i found a 32gb ssd, maybe i could put truenas on this ssd.


thanks

Translated with www.DeepL.com/Translator (free version)
...

I don't know if that exact model, Broadcom / LSI 2308, can be flashed to IT mode. But, yes, IT mode is what we want, (IT = Integrated Target). The links I left may have some pointers about that specific model.

Yes, a 32GB SSD would be perfectly fine for a TrueNAS boot pool. In general, SATA SSDs, (or small hard drives), are more reliable for TrueNAS boot pools than USB flash drives. Many USB flash drives are designed to be the cheapest they can be, with the result is that wear out sooner. Or are outright unreliable.

...
I didn't understand this point.
I understand that it is the exact opposite of the above :)

Just making the point for others that read this. Data Center use of ZFS can be radically different from TrueNAS in small / medium business or home use.

 

[danb35]

I don't know if that exact model, Broadcom / LSI 2308, can be flashed to IT mode.

It can; the 2008/2380 series are probably the best-known and best-tested controllers around here.

 

[trisonic]

Perfect!!!

I just flashed the IT firmware and installed truenas on the small ssd.... Now the fun begins!

Thanks