zfs discuss - Aug 2008 - EMC - top of the table for efficiency, how well would ZFS do?

Just saw this blog post linked from the register, it''s EMC pointing out
that their array wastes less disk space than either HP or NetApp.  I''m
loving the 10% of space they have to reserve for snapshots, and you
can''t add more o_0.

HP similarly recommend 20% of reserved space for snapshots, and NetApp recommend
a whopping 100% (that was one reason we didn''t buy NetApp actually).

Could anybody say how ZFS would match up to these figures?  I''d have
thought a 14+2 raid-z2 scheme similar to NFS'' would probably be
fairest.

http://chucksblog.typepad.com/chucks_blog/2008/08/your-storage-mi.html

Ross
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Netapp does NOT recommend 100 percent.  Perhaps you should talk to
netapp or one of their partners who know their tech instead of their
competitors next time.

Zfs, the way its currently implemented will require roughly the same
as netapp... Which still isn''t 100.



On 8/30/08, Ross <myxiplx at hotmail.com> wrote:
> Just saw this blog post linked from the register, it''s EMC
pointing out that
> their array wastes less disk space than either HP or NetApp.  I''m
loving the
> 10% of space they have to reserve for snapshots, and you can''t add
more o_0.
>
> HP similarly recommend 20% of reserved space for snapshots, and NetApp
> recommend a whopping 100% (that was one reason we didn''t buy
NetApp
> actually).
>
> Could anybody say how ZFS would match up to these figures?  I''d
have thought
> a 14+2 raid-z2 scheme similar to NFS'' would probably be fairest.
>
> http://chucksblog.typepad.com/chucks_blog/2008/08/your-storage-mi.html
>
> Ross
> --
> This message posted from opensolaris.org
> _______________________________________________
> zfs-discuss mailing list
> zfs-discuss at opensolaris.org
> http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
>

Hey Tim,

I''ll admit I just quoted the blog without checking, I seem to remember
the sales rep I spoke to recommending putting aside 20-50% of my disk for
snapshots.  Compared to ZFS where I don''t need to reserve any space it
feels very old fashioned.  With ZFS, snapshots just take up as much space as I
want them to.

The problem though for our usage with NetApp was that we actually
couldn''t reserve enough space for snapshots.  50% of the pool was their
maximum, and we''re interested in running ten years worth of snapshots
here, which could see us with a pool with just 10% of live data and 90% of the
space taken up by snapshots.  The NetApp approach was just too restrictive.

Ross

> Date: Sun, 31 Aug 2008 08:08:09 -0700
> From: tim at tcsac.net
> To: myxiplx at hotmail.com; zfs-discuss at opensolaris.org
> Subject: Re: [zfs-discuss] EMC - top of the table for efficiency, how well
would ZFS do?
> 
> Netapp does NOT recommend 100 percent.  Perhaps you should talk to
> netapp or one of their partners who know their tech instead of their
> competitors next time.
> 
> Zfs, the way its currently implemented will require roughly the same
> as netapp... Which still isn''t 100.
> 
> 
> 
> On 8/30/08, Ross <myxiplx at hotmail.com> wrote:
> > Just saw this blog post linked from the register, it''s EMC
pointing out that
> > their array wastes less disk space than either HP or NetApp. 
I''m loving the
> > 10% of space they have to reserve for snapshots, and you
can''t add more o_0.
> >
> > HP similarly recommend 20% of reserved space for snapshots, and NetApp
> > recommend a whopping 100% (that was one reason we didn''t buy
NetApp
> > actually).
> >
> > Could anybody say how ZFS would match up to these figures? 
I''d have thought
> > a 14+2 raid-z2 scheme similar to NFS'' would probably be
fairest.
> >
> > http://chucksblog.typepad.com/chucks_blog/2008/08/your-storage-mi.html
> >
> > Ross
> > --
> > This message posted from opensolaris.org
> > _______________________________________________
> > zfs-discuss mailing list
> > zfs-discuss at opensolaris.org
> > http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
> >
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On Sun, Aug 31, 2008 at 10:39 AM, Ross Smith <myxiplx at hotmail.com>
wrote:
>  Hey Tim,
>
> I''ll admit I just quoted the blog without checking, I seem to
remember the
> sales rep I spoke to recommending putting aside 20-50% of my disk for
> snapshots.  Compared to ZFS where I don''t need to reserve any
space it feels
> very old fashioned.  With ZFS, snapshots just take up as much space as I
> want them to.
>
Your sales rep was an idiot then.  Snapshot reserve isn''t required at
all.
It isn''t necessary to take snapshots.  It''s simply a portion
of space out of
a volume that can only be used for snapshots, live data cannot enter into
this space.  Snapshots, however, can exist on a volume with no snapshot
reserve.  They are in no way limited to the "snapshot reserve"
you''ve set.
Snapshot reserve is a guaranteed minimum amount of space out of a volume.
You can set it 90% as you mention below, and it will work just fine.

ZFS is no different than NetApp when it comes to snapshots.  I suggest until
you have a basic understanding of how NetApp software works, not making ANY
definitive statements about them.  You''re sounding like a fool and/or
someone working for one of their competitors.

>
>
> The problem though for our usage with NetApp was that we actually
couldn''t
> reserve enough space for snapshots.  50% of the pool was their maximum, and
> we''re interested in running ten years worth of snapshots here,
which could
> see us with a pool with just 10% of live data and 90% of the space taken up
> by snapshots.  The NetApp approach was just too restrictive.
>
> Ross
>
There is not, and never has been a "50% of the pool maximum". 
That''s also a
lie.  If you want snapshots to take up 90% of the pool, ONTAP will GLADLY do
so.  I''ve got a filer sitting in my lab and would be MORE than happy to
post
the df output of a volume that has snapshots taking up 90% of the volume.


--Tim
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On Sun, Aug 31, 2008 at 11:06:16AM -0500, Tim wrote:
> > The problem though for our usage with NetApp was that we actually
couldn''t
> > reserve enough space for snapshots.  50% of the pool was their
maximum, and
> > we''re interested in running ten years worth of snapshots
here, which could
> > see us with a pool with just 10% of live data and 90% of the space
taken up
> > by snapshots.  The NetApp approach was just too restrictive.
> 
> There is not, and never has been a "50% of the pool maximum". 
That''s also a
> lie.  If you want snapshots to take up 90% of the pool, ONTAP will GLADLY
do
> so.  I''ve got a filer sitting in my lab and would be MORE than
happy to post
> the df output of a volume that has snapshots taking up 90% of the volume.
Even so, I don''t think snapshots is really what he needs.  It sounds a
lot like
what he really needs is an HFS like SAM.  That''s just my opinion though
maybe.
10 years of snapshots sounds an awful lot like backups to me, and there are much
better ways to handle that then with snapshots (on any filesystem).

-brian
-- 
"Coding in C is like sending a 3 year old to do groceries. You gotta
tell them exactly what you want or you''ll end up with a cupboard full
of
pop tarts and pancake mix." -- IRC User (http://www.bash.org/?841435)

Dear god.  Thanks Tim, that''s useful info.

The sales rep we spoke to was really trying quite hard to persuade us that
NetApp was the best solution for us, they spent a couple of months working with
us, but ultimately we were put off because of those
''limitations''.  They knew full well that those were two of our
major concerns, but never had an answer for us.  That was a big part of the
reason we started seriously looking into ZFS instead of NetApp.

If nothing else at least I now know a firm to avoid when buying NetApp...

Date: Sun, 31 Aug 2008 11:06:16 -0500
From: tim at tcsac.net
To: myxiplx at hotmail.com
Subject: Re: [zfs-discuss] EMC - top of the table for efficiency, how well would
ZFS do?
CC: zfs-discuss at opensolaris.org



On Sun, Aug 31, 2008 at 10:39 AM, Ross Smith <myxiplx at hotmail.com>
wrote:






Hey Tim,

I''ll admit I just quoted the blog without checking, I seem to remember
the sales rep I spoke to recommending putting aside 20-50% of my disk for
snapshots.  Compared to ZFS where I don''t need to reserve any space it
feels very old fashioned.  With ZFS, snapshots just take up as much space as I
want them to.

Your sales rep was an idiot then.  Snapshot reserve isn''t required at
all. It isn''t necessary to take snapshots.  It''s simply a
portion of space out of a volume that can only be used for snapshots, live data
cannot enter into this space.  Snapshots, however, can exist on a volume with no
snapshot reserve.  They are in no way limited to the "snapshot
reserve" you''ve set. Snapshot reserve is a guaranteed minimum
amount of space out of a volume.  You can set it 90% as you mention below, and
it will work just fine.


ZFS is no different than NetApp when it comes to snapshots.  I suggest until you
have a basic understanding of how NetApp software works, not making ANY
definitive statements about them.  You''re sounding like a fool and/or
someone working for one of their competitors.

 

The problem though for our usage with NetApp was that we actually
couldn''t reserve enough space for snapshots.  50% of the pool was their
maximum, and we''re interested in running ten years worth of snapshots
here, which could see us with a pool with just 10% of live data and 90% of the
space taken up by snapshots.  The NetApp approach was just too restrictive.


Ross
 There is not, and never has been a "50% of the pool maximum". 
That''s also a lie.  If you want snapshots to take up 90% of the pool,
ONTAP will GLADLY do so.  I''ve got a filer sitting in my lab and would
be MORE than happy to post the df output of a volume that has snapshots taking
up 90% of the volume.



--Tim




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I''ve read the same log entry, and was also thinking about ZFS...

Pillar Data Systems is also answering to the call
http://blog.pillardata.com/pillar_data_blog/2008/08/blog-i-love-a-p.html

BTW: Would transparent compression be considered as cheating? :-)
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