Switching SATA cables and plugs

[jyavenard]

Well if it actually says that in the solaris manual, then, I suppose we should be giving that advice officially at all times.

Thanks for that Jyavenard.

That link is actually from the FreeNAS manual as posted there:
http://forums.freenas.org/threads/ecc-vs-non-ecc-ram-and-zfs.15449/page-4#post-83743

FreeNAS 9.1 Guide Section 6.3.9 "If you will be moving a ZFS drive from one system to another, perform this

http://docs.huihoo.com/opensolaris/solaris-zfs-administration-guide/html/ch04s06.html

exportation first. This operation flushes any unwritten data to disk, writes data to the disk indicating that the export was done, and removes all knowledge of the pool from the system".

But yeah, the FreeNAS manual is also wrong, because ... it's not solaris...

 

[DrKK]

I look at it this way.

The Solaris guys *wrote* ZFS. There's no harm in EXPORTING the pool. Right? Let's just export the pool. It won't hurt anything to advise users to export the pool.

 

[cyberjock]

Yeah, the manual has a lot of errors. I've given up trying to fix them because 9.2.0 is supposed to be kind of rewritten by Dru(our manual maintainer). I've fixed a few things, but I don't like barging in and rewriting stuff(even if I think my stuff is an improvement) since she's a very well known document writer and I don't want to do something that messes up her system.

We were just discussing last night in IRC that RAID3 isn't mentioned in the beginning of the manual as a RAID type, but when you create a UFS array RAID3 is an option and it actually mentions how to use it properly.

 

[jyavenard]

I mentioned one way to reproduce the issue of a pool not properly mounting if you didn't export it earlier (http://forums.freenas.org/threads/ecc-vs-non-ecc-ram-and-zfs.15449/page-4#post-85375)

Here is another, this time only using FreeNAS.

Create a zfs pool (RAIDZ2 , 6 drives), using 6 ports on a LSI adapter (X10SL7-F supermicro motherboard). Create the pool using the device name (and not the gptid, which is typical on how a pool would have been created in another system)

zpool create pool raidz2 da0 da1 da2 da3 da4 da5

halt system.

plug it into another machine (identical to machine #1, also running freenas (9.1.1)), this time however, connect 2 disks to LSI adapter (da6 and da7) , and 4 disks to intel adapter (ada0 ada1 ada2 ada3).
boot. pool won't mount as it wasn't exported earlier, so you have to use zpool import -f poolid pool (I already had a zpool named pool on the 2nd system, so couldn't do zpool import pool)

now halt second system.

Put back the 6 drives in the first machine.
However, put it such as the first 3 drives are back on their original LSI sata ports (da0 da1 da2); and the 3 remaining disk are put on the 3 intel SATA ports (ada0, ada1, ada2). Boot

pool has been imported but is degraded; doing zpool export pool followed by zpool import -f pool and all is good and back to normal.

Similar scenario as what I had done with linux earlier in the end...
It's unlikely someone who has only ever used freenas GUI would experience such scenario, but you never really know how or where the pool got created in the first place. It's also not uncommon for people to create their pool using the command line, such as when using a partition rather than the full disk (GUI doesn't let you do that)

So really... Export your pool if you can before using it in another system or changing hardware. Probably won't do anything if you didn't, but will save you heaps of headaches if you do in the event you do have issues.
That's what the manual state anyway, and as everyone knows, you should always follow the manual to the letter :)

 

[cyberjock]

So really... Export your pool if you can before using it in another system or changing hardware. Probably won't do anything if you didn't, but will save you heaps of headaches if you do in the event you do have issues.

That's what the manual state anyway, and as everyone knows, you should always follow the manual to the letter :)

You do realize that I have made changes to the manual, so in some regard what I say might as well be as good as being from the manual. LOL.

In fact, I'm in discussion with someone over this. If you export an encrypted pool things don't.... go well... in the long term. So that comment might be going away anyway. Gonna put my test system together and do some experimenting.