[ale] ZFS on Linux

[Derek Atkins]

Ed Cashin <ecashin at noserose.net> writes:

> Thanks in advance for the notes you take.  I'm interested to hear what you
> find.
>
> By the way, work sent me to a Nexenta course in 2010 where I learned ZFS stuff
> from Richard Elling:
>
>   http://www.richardelling.com/
>
> ... and one thing that kept coming up is how users usually reach for the
> RAID-Z options when stripes of mirrors would perform better and offer more
> flexibility.  I thought that was notable.

I suspect people want more storage options.  A mirror+stripe solution
implies 100% overhead, so if you have e.g. 10 1TB disks (10TB total) you
only get 5TB of usable storage.  OTOH if you use something like RaidZ or
RaidZ2 then you get more storage capacity out of the same 10 drives.  So
I think that's why people use RaidZ instead of Stripe+Mirror.

Me, I'm still researching to figure out what's the best option for my
future use.  I'd like to be able to add more drives to expand the array.
I'd like to be able to replace the drives (potentially with larger
drives) and have the system expand the array when possible.  I'd like to
be able to rebalance the system as I add more storage over time.  But
I'd also like to have redundancy such that I can theoretically lose more
than one drive and still survive (which would be a major issue if I had
an 20 or 24-drives in use).  So I'm not sure if a Stripe+Mirror or
"RaidZ" or potentially a set of striped RaidZs would be better for me.

I wonder how long until we see a LinNAS (ala FreeNAS but built on
Linux)?

-derek

-- 
       Derek Atkins, SB '93 MIT EE, SM '95 MIT Media Laboratory
       Member, MIT Student Information Processing Board  (SIPB)
       URL: http://web.mit.edu/warlord/    PP-ASEL-IA     N1NWH
       warlord at MIT.EDU                        PGP key available