[Lustre-discuss] upgrade to 1.8.4 and test fallback to 1.6.7.2

[Ms. Megan Larko]

Greetings!

I performed an upgrade of our Lustre file system and corresponding
SuSE kernel.   The Lustre upgrade went well.  After the upgrade from
1.6.7.2 to 1.8.4 I was able to mount my Lustre volumes.   The data was
fine.    The quotas started on mount via the lustre params on the MDT
and OSTs.

I attempted to add a new lustre tuning parameter to my system (I
wanted to add the *t.group_upcall=NONE.)   While the Lustre 1.8.4 read
the 1.6.7.2 tuning parameters without issue and I could add to the
parameters under 1.8.4 without issue, if I tried to change a parameter
requiring that I use the --writeconf option, I learned I had to change
all the parameters from the 1.6.7.2 syntax to the 1.8.4 syntax.
(EXAMPLE:   "failover.node" string became "failnode")    Okay.  This I
can do,   BUT...

If I have to revert to 1.6.7.2 (due to a security flaw in the linux
kernel or something...) am I correct in assuming that the lustre 1.8.4
parameter strings would not be understood by the 1.6.7.2 lustre system
(can't have s/w reading into the future, right?   Smile)?   If that is
the case, then I should not change my lustre 1.6.7.2 parameters into
the newer 1.8.4 strings until I am certain I won't have to revert
back, or be prepared to do a full --writeconf of all *Ts to use the
older 1.6.7.2 strings after going back to the previous kernel
containing the lustre 1.6.7.2 files.

Am I correct on this understanding?

Thanks,
Megan Larko

SGI Federal