Sanity check for migration from one pool to a bigger one

[Agurri]

Current configiuration

Asrock C2550D4I
16gb RAM (planing to upgrade)
FreeNAS-11.2-U8

4x 6TB Western Digital RED in RAIDZ2 with only one pool called Volume1.
24tb raw, 10.5 usable

I'm currently at 95% full and around 400gb left. It's time to do some upgrade to the system since I really haven't touched it for a while now. The last time I did an upgrade was 2 years ago when I changed my 2tb HDD to the 6tb giving me more space. While the 4x RAIDZ2 configuration was fine with me even if it meant losing more than 50%, I decided to buy 3 more 6tb WD Red, the same type I already have. At the same time I bought my newer 6tb, I also bought a 10tb external HDD that will ultimately be used as an external backup to the system. But, keep in mind this HDD could be used in some way for the migration.

Now, I'm torn on how to upgrade/migrate everything.

I would like to have a configuration of 7x6TB in RAIDZ2 with only one pool, pretty much the same type as I have right now.

Current pool

HDD1
HDD2
HDD3
HDD4

I would detach HDD 3 and HDD4 from my Volume1 pool, making my initial pool degraded.

HDD1
HDD2
*missing*
*missing*

I would then create a new degraded pool, name Volume2 consisting of

HDD3
HDD4
HDD5
HDD6
HDD7
*missing*
*missing*

I think you pretty much see where I'm going with this. I would migrate from Volume1 to Volume2 in FreeNAS. This would be ideal because I would keep everything intact. Dataset, permission, jails, etc. After the migration is completed, I would detach HDD1, and HDD2, destroy the Volume1 pool, and attach them to the Volume2 pool, thus beginning the resilvering process.

Suffice to say it would be the most dangerous way of doing it. During the migrating process, if there's one failure, I'm out of everything.

One thing I could do is temporary to take out my 10tb HDD and use it as a place holder for the Volume2 pool,

Volume1 during migration would be
HDD1
HDD2
HDD3
*missing*

Volume2 would be
HDD4
HDD5
HDD6
HDD7
HDD10tb
*missing*
*missing*

So, at least, if my main pool suffers from a disk failure, I'm still somewhat protected.

What do you think about that ? Is there a better way of doing it ?

Regards

 

[JaimieV]

Plan B is safer. For small values of safe.

Possible plan C: copy all your data onto the 10gig (there's a little overspill which you can surely find somewhere else to put), and then do Plan A.

Plan D: Order enough 6TB drives for the transition, then abuse Amazon's returns policy by sending them back after you're done.

Plan E: If you're using the 10TB as a backups drive, it's already too small. Order a 14TB and use that in tandem with plans B or C. Then send the 10TB back.

By the way, WD Red 6TB are potentially SMR if they're Plus drives. Have you made sure they're not? Check here: https://blog.westerndigital.com/wd-red-nas-drives/

 

[Agurri]

Yup, I made sure they were WD60EFRX and not WD60EFAX.

The backup 10tb would not have been a full/complete backup of the NAS, only essentials stuff. So 10 if ok for the moment.

What I didn't like about the C plan was how accurate would the copy be. I would have to redo the dataset and everything. I might also try to delete some non-essential or redundant stuff on the NAS to make up 1 TB and be able to fit everything on the 10TB

But at least, it seems I'm in the good direction to upgrade my drives.

 

[JaimieV]

I mean, don't trust me that much - I'm a home user (admittedly with decades of sysadmin/devops work experience and ~8 years of using FreeNAS) not an active commercial-grade storage geek. I'd go with plan D myself, except probably keep all the drives. They'll come in handy eventually as older drives die. Even going with just one more 6TB will get you single-redundancy on both pools throughout the operation.

Plan F: Pump all your data up to AWS S3 or Backblaze. Takes a while, but...

 

[Agurri]

I know that ordering all of my HDD thru Amazon and return them could be a solution. I just don't find it ... nice to do.

Having another HDD for a tempory raidz1 on both pool might be a good idea. I'll try to look around if someone has a HDD I can temporary use.

Thanks for the heads up !

 

[Scharbag]

Creating a degraded pool is, well, not awesome... But I see where you are going.

I would likely not attempt this. I would back-up everything and start over. Buy 1 more 10TB disk and make it a mirror backup then blow up your pool and start over.

Cheers,