[RFC] Planning install on LSI MegaRAID SAS 9271-8i (no HBA mode)

[darkwarrior]

Let me remind you of Scott Adams' Dilbert's Principle. Namely,
Everyone is an idiot, not just the people with low SAT scores. The only differences among us is that we're idiots about different things at different times. No matter how smart you are, you spend much of your day being an idiot.
Scott Adams, The Dilbert Principle

I wish I will observe (laugh at) you be you at my position back in summer, ha-ha. BTW, the Very Big Volume is Ok, ZFS and FreeNAS tolerated the morons, I restored it easily. The whole setup with FreeNAS/ZFS over a bunch of "one disk per logical RAID0 volume exported by LSI MegaRAID" is by far not the worse thing I have seen in my long life. I won't recommend this kind of setup, but is is a viable option in absence of better ones.

Strange, how some people react sometimes ...
I was not calling you an Idiot ... so I would have preferred if you did not either ...
And I'm not wishing to anybody to loose data either ... But I'm sure it happened to everybody at some point.

BTW: The morons I was talking about was your former employer, but you seem to know better ...

And to end with a citation as well:
Me, 'I know that I know nothing' Socrates

 

[Andrii Stesin]

Wow, sorry, in any case, I wasn't speaking about you. That's a story of mine myself :) please take my apologies for miscommunication.

Technically, the result is:

1. The setup of ZFS over MegaRAID's-exported "1 disk per logical RAID0 volume" is not recommended, but is perfectly viable. It works well until human factor makes its way in the game. BTW take a look at calomel.org pages devoted to this kind of setup, it's not that bad at all.
2. MegaRAID is a somewhat strange beast compared to say LSI dumb-HBA in the case of incorrect physical treatment. But there wasn't any data loss in the result. Broken MegaRAID's metadata didn't affect even a bit of business data stored on disks, and the volume was recovered easily after cleaning broken "foreign configuration" from the drives, retagging them into the previous state, and FreeNAS imported the volume back without a glitch.

 

[MatthewSteinhoff]

FreeNAS imported the volume back without a glitch.

LOL! Yeah, 'without a glitch' except for everything that happened right up until the import.

Cheers,
Matt

 

[Andrii Stesin]

LOL! Yeah, 'without a glitch' except for everything that happened right up until the import.

Whatever happened up until the import was not in any way the FreeNAS or ZFS problem. That was a problem of crooked-handed morons, multiply on developers of LSI MegaRAID firmware, which can not correctly handle occasional physical disconnect and reconnect of external SAS disk rack. As soon as mechanical and cable issues were settled back, and lost configuration restored to LSI and the disks, FreeNAS performed recovery flawlessly.