[ale] ZFS on Linux
Jim Kinney
jim.kinney at gmail.com
Mon Apr 22 13:43:26 EDT 2013
starting from scratch on this is my preference but it's not in the budget.
Parking 70TB "elsewhere" for a 4 array reformat while NOT buying new drives
is a challenge.
On Mon, Apr 22, 2013 at 1:24 PM, Derek Atkins <warlord at mit.edu> wrote:
> Jim Kinney <jim.kinney at gmail.com> writes:
>
> > given what the drive arrays are used for, dedup is a big plus (people
> make
> > copies and copies of research files like drive space is $0!). And, yeah,
> even
> > with no dedup, 32G is not going to cut it anyway.
>
> You can get mobos that support 256MB for not too much money.
>
> For my case I cannot imagine that dedup would significantly help me; my
> plan is to store audio and video, and perhaps *some* VM data, but most
> likely I don't imagine that dedup would do *me* any signigicant
> advantage.
>
> > The checksums for RAID6 are the same as in raidz2.
>
> Are they? I though ZFS/RAID-Z(2) had additional checksums above and
> beyond what RAID5(6) provided, such that it could detect and correct a
> write-hole (or other) disk/storage failure.
>
> > I found a 250G SSD but can't use it. I have one other system I can put
> it on
> > but it has not enough PCIe slots for the need.
> >
> > the solution to all of this is $$$$$ for new system :-(
>
> Or just replace the mobo ;)
>
> -derek
>
> > On Fri, Apr 19, 2013 at 11:58 AM, Derek Atkins <warlord at mit.edu> wrote:
> >
> > Jim,
> >
> > Jim Kinney <jim.kinney at gmail.com> writes:
> >
> > > After much research, I have decided to NOT implement ZFS. The main
> > factors of
> > > interest were the raidz2 and data deduplication. In order to
> support the
> > > deduplication,the server needs 5G RAM per 1TB storage. That's a
> deal
> > breaker
> > > right there as the system to be used will only support 32G and has
> 50TB.
> > > Raidz2 is basically software RAID6 which I can already do.
> > >
> > > Looked at getting an SSD for the deduplication data and using
> l2arc but
> > I have
> > > no space to install it on that server. Grr.
> >
> > Do you really feel you need ZFS deduplication? According to
> > http://doc.freenas.org/index.php/Hardware_Recommendations you only
> need
> > 5GB/TB if you're using dedup. If you're just using ZFS then they
> > recommend 1GB/TB. Granted, if you've got 50TB of data then a 32GB
> > memory limit wont be useful to you.
> >
> > However, thank you for making me look at that; I was considering a
> > 32GB-limit Mobo for my system, which I was expecting to start at 12TB
> > usable but potentially expanding to 96TB. I don't think a 96TB ZFS
> > would work well with 32GB memory.
> >
> > OTOH, is ZFS really only just "RAID6"? I thought that the ZFS
> checksums
> > would provide improved data integrity (scrubbing) over pure RAID6?
> >
> > -derek
> >
> > > On Fri, Mar 29, 2013 at 3:10 PM, Ed Cashin <ecashin at noserose.net>
> wrote:
> > >
> > > 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.
> > >
> > > On Fri, Mar 29, 2013 at 2:44 PM, Jim Kinney <
> jim.kinney at gmail.com>
> > wrote:
> > >
> > > There was an update to this that just hit /.
> > >
> > > WooHoo!
> > >
> > > I have not used ZFS (minimal solaris experience) before
> but I
> > have a
> > > situation where raidz looks like a very good choice. An
> external
> > 16
> > > bay JBOD box hanging off a SAS HBA looks like a prime
> candidate.
> > The
> > > big issue for me is the support for native NFSv4 ACLs which
> > solves
> > > some issues.
> > >
> > > As I go through this exercise, I'll keep some notes and
> maybe
> > look at
> > > a presentation on doing this.
> > >
> > > hints, gotcha's, are very welcome.
> > >
> > > I did find a pdf of the zfsadmin.pdf http://pdfhome.org/
> > zfsadmin.pdf
> > >
> > > --
> > > --
> > > James P. Kinney III
> > >
> > > Every time you stop a school, you will have to build a
> jail.
> > What you
> > > gain at one end you lose at the other. It's like feeding a
> dog
> > on his
> > > own tail. It won't fatten the dog.
> > > - Speech 11/23/1900 Mark Twain
> > >
> > > http://electjimkinney.org
> > > http://heretothereideas.blogspot.com/
> > >
> > > _______________________________________________
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> > >
> > > --
> > > Ed Cashin <ecashin at noserose.net>
> > > http://noserose.net/e/
> > > http://www.coraid.com/
> > >
> > > _______________________________________________
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> > >
> > > --
> > > --
> > > James P. Kinney III
> > >
> > > Every time you stop a school, you will have to build a jail. What
> you
> > gain at
> > > one end you lose at the other. It's like feeding a dog on his own
> tail.
> > It
> > > won't fatten the dog.
> > > - Speech 11/23/1900 Mark Twain
> > >
> > > http://electjimkinney.org
> > > http://heretothereideas.blogspot.com/
> > >
> > > _______________________________________________
> > > Ale mailing list
> > > Ale at ale.org
> > > http://mail.ale.org/mailman/listinfo/ale
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> >
> > --
> > 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
> >
> > _______________________________________________
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> >
> > --
> > --
> > James P. Kinney III
> >
> > Every time you stop a school, you will have to build a jail. What you
> gain at
> > one end you lose at the other. It's like feeding a dog on his own tail.
> It
> > won't fatten the dog.
> > - Speech 11/23/1900 Mark Twain
> >
> > http://electjimkinney.org
> > http://heretothereideas.blogspot.com/
> >
> > _______________________________________________
> > Ale mailing list
> > Ale at ale.org
> > http://mail.ale.org/mailman/listinfo/ale
> > See JOBS, ANNOUNCE and SCHOOLS lists at
> > http://mail.ale.org/mailman/listinfo
>
> --
> 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
>
> _______________________________________________
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>
--
--
James P. Kinney III
*
*Every time you stop a school, you will have to build a jail. What you gain
at one end you lose at the other. It's like feeding a dog on his own tail.
It won't fatten the dog.
- Speech 11/23/1900 Mark Twain
*
http://electjimkinney.org
http://heretothereideas.blogspot.com/
*
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