Replacing a 2TB HDD with a 3TB with no spare SATA ports

[twentyseven]

I have a 5x2TB WD Red ZFS Freenas
Build FreeNAS-9.3-CURRENT-201503161938
Platform AMD Phenom(tm) 9750 Quad-Core Processor
Memory 7909MB

I need to replace one of the disks, and this is slightly out of my comfort level. I have a replacement 3TB WD Red drive that I would like to use in place of the failing 2TB drive. My plan is that over the next 12 months, I will replace all the drives with 3TB (I am in no hurry). The documentation is clear on how to replace, but where larger capacity drives are involved it seems to suggest a scenario where I should use an open SATA port, but I don't have one.

I want to do the following:
1. Power off
2. Replace the drive (i.e. remove the 2TB and put the 3TB on the same slot)
3. Let it resliver

I assume that only 2TB of the new 3TB drive will be used for the RAID (and the 1TB will be unusable). I am hoping that when all 5 drives are replaced with 3TB drives, I will get back the unused 1TB on each drive.

Are my assumptions correct? Is there a better approach?

Thanks in advance.

 

[hugovsky]

Assuming you are using raidz2, you should be good.

 

[twentyseven]

I am at raidz1. So if I take my proposed plan of action, I run the risk of losing data if a problem arises while the sliver is happening, yes?

 

[hugovsky]

Exactly. How much space are you using in current pool?

 

[twentyseven]

I have 3.5TB of data of 5.5TB available

 

[Robert Trevellyan]

The documentation is clear on how to replace, but where larger capacity drives are involved it seems to suggest a scenario where I should use an open SATA port, but I don't have one.

I want to do the following:
1. Power off
2. Replace the drive (i.e. remove the 2TB and put the 3TB on the same slot)
3. Let it resliver

If you don't have a spare SATA port, you can do one of the following:

1. Follow the directions for replacing a failed drive, accepting the fact that your pool will be degraded until the resilver is complete. Note that step 1 is to offline the drive to be replaced in the GUI, NOT to power off the machine.
2. Buy an eSATA expansion card and a hard drive dock and follow the directions for replacing a drive when you have a spare disk port.

I've successfully done the latter, using a Rosewill RC-219 and a StarTech SATADOCK22UE.

 

[joeschmuck]

You of course run the risk of complete data loss if you have a hard drive failure of one of your other five hard drives just because you created a RAIDZ1 pool but you knew that risk when you created the pool in the first place but that doesn't mean you can't replace the failing drive, actually you must replace it if it is in fact failing. You should at least have any important data backed up but replace the drive regardless because it's failing already. Follow the user guide for replacing a failing hard drive. http://doc.freenas.org/9.3/freenas_storage.html#replacing-a-failed-drive

Not sure where this need for a spare SATA port comes from, sure it's nice but it's not really needed either. So many of us would be screwed if that were the case. Follow the guide, it works. Also, if your system can handle hot swapping your drives DO NOT do it, Power down before replacing the drive.

And about the pool expanding, yes you have it correct, once all the drives have been replaced with 3TB drives the pool will automatically expand but not before. This has to do with the fact that all the data is evenly striped across all the drives so you are limited by the smallest drive in the pool.

EDIT: If you can reduce the size of the data on your pool (delete old backup files say) then the resilvering will be quicker but it will take a little bit of time, possibly overnight.