Best way to add DAS / external disks to a Microserver?

[CompuGlobalHyperMegaNet]

I'm currently planning my next big server disk upgrade and I'd like some advice on the best way to go about it given various criteria.

I have two FreeNAS servers. "X10" is my primary server and "Gen8" is the backup. Their specs are as follows.

Primary server, aka "X10"
FreeNAS 9.10.2-U5 11.2-U5 finally!!!
CPU: Intel Xeon E3-1220v3
Mobo: Supermicro X10SL7-F
RAM: 32GB Crucial DDR3 ECC 1600 RAM
Boot: Sandisk X400 128GB SSD... I had it laying around and USB sticks fail too often.
HDD: 8x WD Red 3TB in RAIDz2
PSU: Seasonic SS-660XP2
UPS: APC Smart-UPS SMT1500i

Backup server, aka "Gen8"
FreeNAS 11.2-u4.1
SYSTEM: HPE MicroServer Gen8
CPU: Intel Celery G1610T
RAM: 2GB of HP + 8GB of Crucial DDR3 ECC 1600 RAM
HDD: 4x Seagate IronWolf 8TB in 2x mirrors
UPS: APC Smart-UPS SMT1500i

Here's the rough plan I have worked out.

1. Purchase 8x 8TB disks and burn them in. [EDIT] 6x 10TB or 6x 12TB Toshiba N300's might be an option.
2. Make a fresh snapshot of X10.
3. Replicate the snapshot to Gen8.
4. Disconnect the 8x 3TB RAIDz2 pool from X10.
5. Connect the 8x 8TB disks to X10 in a RAIDz2.
6. Replicate the data from Gen8 to the new X10 pool.
7. Verify everything is hunky dory.
8. Change Gen8's 2x mirrored 2x 8TB vdevs to a single 4x 8TB RAIDz2.
9. Send snapshot of X10 to the new Gen8 pool (meaning that I'm back to having three copies of my data).
10. ????????
11. Add the 3x 8TB disks to the same pool as the 4x 8TB RAIDz2.

It's steps 10 and 11 where I need a little help.

For step 10...

I need to figure out the best way of connecting the old 8x 3TB pool to Gen8 without breaking the bank. My working idea is to get a HBA, a second PSU and a Supermicro CSEPT-JBOD-CB1, a nifty little PCB that controls disk and fan power in external, disk only chassis. I need to look into the Supermicro board in more detail though, specifically whether my Gen8 will play nice with it or whether any of the Gen8's idiosyncrasies would be problematic.

I'd keep the Gen8 hardware unnchanged aside from the addition of a HBA and cables run from it to a second chassis (a Fractal Design Define XL R2 I have laying around).

A decent PSU would set me back £50 to £60 quid, the Supermicro control board is £40 minus shipping and I'm not sure how much a decent HBA is going for these days but let's call the grand total, for all three items, £200.

Are there any other options I should be looking at with a budget of ~£200?

For step 11...

Aside from slightly better hardware failure scenarios, is there any upside to having the 4x 8TB RAIDz2 vdev and the 8x 3TB vdev in separate pools? It would create some extra work with dataset sizes and replication on/from X10. You could also argue that having two pools on Gen8 would eliminate the need for and risk associated with step 8 as I would need to blow away the 2x 8TB mirrored vdevs.... feel free to chip in your two cents on the subject.

 

[MatthewSteinhoff]

If it were me, I'd be thinking longer term. I always want at least one empty drive bay so I can expand on the fly by migrating data from small drive to large drive without having to create a new pool. Upgrade in place!

You can find some good deals on external drive cabinets. Here is a 12-bay HP storage unit (with trays!) for US $325...
https://www.ebay.com/itm/HP-Storage...12x-3-5-HDD-Trays-2x-AJ940-04402/173519723538

That's on the high side of pricing but it was the first one I saw with trays. I use the exact same model with one of my FreeNAS servers. Quality, dual power, dual path, enterprise grade, etc. I've seen them as low as $175. Just make sure they include the drive trays with the unit. Buying trays individually will break the bank.

Add an LSI card with two external ports for $50 and a SAS cable for $15...
https://www.ebay.com/itm/LSI-SAS920...ps-IT-Mode-ZFS-FreeNAS-unRAID-US/142909278706
https://www.ebay.com/itm/1m-28AWG-E...to-Mini-SAS-26-Pin-SFF-8088-N6T6/113961743016

For under US $400 (£ 310?), you get 12 hot-swap bays and a near-effortless way to shuffle your data around. The LSI card above has two ports so you could add another D2600 directly without having to daisy chain. (I think you can daisy chain up to three D2600s together. So, with one LSI 9200-8E, you could have 72 drive bays attached to your server. Pretty sweet.)

You could do the same thing with the SuperMicro board, a power supply and some duct tape but the enterprise enclosure is so much cleaner, a lot less time and not that much more than what you'd pay to build your own.

Cheers,
Matt