Hardware RAID 10 with Freenas For iSCSI

[geek0000]

Hello,

My main purpose of running freeNAS is to use iSCSI for a high availability cluster.
Which means reliability is the first priority (which is why the RAID 10 config)

I have a dedicated NAS box with 16GB RAM and quad core processor
1 x SSD (I have installed FreeNAS on this)
4 x 2TB SATA Hard disks with hardware raid (I have configured RAID 10 using the on-board RAID controller)

Now my question!

1) When I access Freenas using the GUI, I click on storage -> volumes -> view disks -> I see 4 disks!
ad1
ad2
ad3
ad4

I was under the impression that a hardware RAID would only show 1 Disk to the operating system. Am I correct?

Is there something wrong with the RAID controller?

2) Is it better to do Hardware raid or software raid?

I believe I could just disable the hardware raid and use the ZFS volume option and could achieve a RAID 10 equivalent solution? If yes how exactly would I do this? as the GUI only shows mirrored or striped option - I don't see a mirrored+ striped option in the ZFS volume manager.

3) Which is easier in terms of disaster recovery?
In case the hard disk fails, is the software RAID process to replace a failed hard disk easy?

Thanks,

 

[geek0000]

Update - I SSH'd into the server and executed this command:
[root@freenas] ~# graid status
Name Status Components
raid/r0 OPTIMAL ada1 (ACTIVE (ACTIVE))
ada2 (ACTIVE (ACTIVE))
ada3 (ACTIVE (ACTIVE))
ada4 (ACTIVE (ACTIVE))
it seems the Graid is automatically created?? and it shows optimal. Why wouldn't it show in the FreeNDS GUI?
and how would FreeBSD "know" to automatically create the raid without me doing anything at all (except doing the raid on the motherboard)

 

[jgreco]

"on board" RAID controller? Is almost certainly software fakeRAID in the BIOS.

zfs doesn't exactly stripe but you can create two mirror vdevs and put them in the same pool. It will get you a similar (but smarter) setup.

 

[geek0000]

I dont see any options for creating "vdev's"

Or is RAIDZ2 is a better option? in terms of reliability?
Cuz I can see an option for ZFS Volume manager through which I can create a RAIDZ2

 

[HoneyBadger]

RAIDZ2 is technically better for reliability since you can have any two disks fail vs a double-fail having the potential to kill your whole pool; however it's bad for VM hosting which it seems like you're doing.

This is almost certainly a software controlled "fake RAID" in your BIOS, and you should disable that option if possible by changing the controller to AHCI mode.

 

[geek0000]

however it's bad for VM hosting which it seems like you're doing.

You mean to say RAIDZ2 is bad for VM hosting?
Hm.. then what would you recommend?

 

[jgreco]

Mirrors.

 

[DJABE]

So running 2 disks in 2 vdev mirrors (4 x 3 TB disks total) is performance wise (ESXi -> iSCSI -> FreeNAS)?

 

[jgreco]

It's better than RAIDZ2.