[ale] ZFS on Linux

Fri Apr 19 12:28:33 EDT 2013

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.

The checksums for RAID6 are the same as in raidz2.

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 :-(

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/
> >
> >     _______________________________________________
> >     Ale mailing list
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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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>
> --
>        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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