Stripe boot volume (not mirror)

[curtii]

Hello, and thanks in advance for any input.

I have just setup FreeNAS for the first time (very excited to start using this software). I used 2x 32GB SSD's as the boot volume. While installing, I did not see any option to specify how multiple drives get configured for boot.

Right now, my understanding is that they would have been configured as the default, a mirrored set. What I'm interested in doing is configuring the boot volume as a striped set. Is this supported with normal functionality, or would it require quite a bit of work?

Also, if anyone has input on how this might benefit the performance of the FreeNAS box, as opposed to a single disk, I'd be very interested to hear thoughts on that as well. I've been running a Proxmox server with a striped SSD boot disk, and have been very happy with the results. Not sure how this will vary for FreeNAS.

Thanks again, and glad to be getting my foot in the door of the FreeNAS community!

 

[BigDave]

Right now, my understanding is that they would have been configured as the default, a mirrored set.

You would have to select both devices during the install phase to make a mirror, but you can also mirror the boot device from the GUI
after the initial installation is completed.

What I'm interested in doing is configuring the boot volume as a striped set. Is this supported with normal functionality, or would it require quite a bit of work?

AFAIK this can not be done, at least not at the time of install, or from the GUI.

You might be able to force this stripe creation (think Frankenstein) through the CLI, but I don't know why you would stripe two drives for a boot device,
other than saving a few seconds of time during updates/reboots. Once FreeNAS boots, the ENTIRE operating system runs from RAM for the most part,
so your speed gains are wasted. It's better to mirror the boot drives for redundancy purposes. Redundancy makes sense for a storage appliance.

On the other hand the mirroring of the storage drives make a difference in performance that is utilized by many users.

 

[pirateghost]

Why on earth would you want the boot device striped?

 

[curtii]

Why on earth would you want the boot device striped?

For performance boost. Not worried about data loss, particularly because they are on SSD's. But I also don't mind losing that data

edit: somehow missed the reply to this that was posted an hour ago

 

[curtii]

You would have to select both devices during the install phase to make a mirror, but you can also mirror the boot device from the GUI
after the initial installation is completed.
AFAIK this can not be done, at least not at the time of install, or from the GUI.

You might be able to force this stripe creation (think Frankenstein) through the CLI, but I don't know why you would stripe two drives for a boot device,
other than saving a few seconds of time during updates/reboots. Once FreeNAS boots, the ENTIRE operating system runs from RAM for the most part,
so your speed gains are wasted. It's better to mirror the boot drives for redundancy purposes. Redundancy makes sense for a storage appliance.

On the other hand the mirroring of the storage drives make a difference in performance that is utilized by many users.

Good to know that there would be negligible performance benefit from modifying the boot device. Now I'm considering utilizing my 2x free SATA ports differently (there's 6 total, and 4 will go to the storage volume), and wondering about a USB boot device (possibly even an old USB 2.0 drive I have kicking around).

I hope this is the scope of this thread, I can create a new one if needed. Just looking to find the best way to utilize the hardware I have at hand, while I save funds for a system built specifically for FreeNAS.

Now what I'm considering is this:

Reinstalling with 2x matching USB 2.0 drives as mirrored boot device
the 2x SSD's setup as a cache for the primary storage volume
the 4x HDD setup as a striped mirror.

 

[pirateghost]

For performance boost. Not worried about data loss, particularly because they are on SSD's. But I also don't mind losing that data

edit: somehow missed the reply to this that was posted an hour ago

Yeah. What performance are you looking for?

The OS runs in memory after booting

 

[curtii]

Yeah. What performance are you looking for?

The OS runs in memory after booting

Similar to Proxmox with a striped boot disk is what I was picturing, but now I understand that's irrelevant for the way FreeNAS works.

Going ahead with setting up 2x mirrored USB sticks as the boot device, 2x striped SSD's as a cache for a 4x HDD storage pool.

 

[anodos]

Similar to Proxmox with a striped boot disk is what I was picturing, but now I understand that's irrelevant for the way FreeNAS works.

Going ahead with setting up 2x mirrored USB sticks as the boot device, 2x striped SSD's as a cache for a 4x HDD storage pool.

Cache? What type of cache? L2ARC isn't terribly useful (and possibly detrimental) on small systems, and a SLOG (ZIL) isn't cache. In general, in the FreeNAS world your RAM is your cache. Want more caching? Add more RAM.

 

[sef]

The OS runs in memory after booting

That's not true with FreeNAS 9.3 and later. That said, there is in fact very little performance loss due to the boot device(s). The main performance improvement you'll see is during upgrades, actually.

(Now, if you wanted to set up a striped boot pool, there are a few ways to do it. The easiest way -- at least, the way I'd do it -- would involve doing an install as normal to a single device, then boot the installer again, import freenas-boot under a different name, partition the stripe devices the same way as the existing boot device, create a new freenas-boot pool using the devices you want to stripe, use zfs send to duplicate it, copy the boot partition from the existing boot device to each of the new boot devices, export both pools, remove the original boot device, reboot, set the BIOS to boot correctly, and voila.)

(Okay, now that I've typed all that, I take it back -- if I were doing it, I'd change the install script to use a raidz1 if the number of install disks was greater than 2. Hm. That is in fact much easier.)

(But doing this is completely unsupported, and there is no support in the GUI to deal with replacing any bad device in the pool. Barring that, upgrades will work properly due to absolute laziness in the post-upgrade scripts meaning it'll work in a raid configuration by pure luck.)