> On Mon, 17 Jul 2006, Roch wrote:
>
> >
> > Sorry to plug my own blog but have you had a look
> at these ?
> >
> >
> http://blogs.sun.com/roller/page/roch?entry=when_to_a
> nd_not_to (raidz)
> >
> http://blogs.sun.com/roller/page/roch?entry=the_dynam
> ics_of_zfs
> >
> > Also, my thinking is that raid-z is probably more
> friendly
> > when the config contains (power-of-2 + 1) disks (or
> + 2 for
> > raid-z2).
>
Yes I did, and please, plug away!! These are awesome blog entries, and
I've read both of them several times. You rule! Really.
I wish I could understood a bit more of your second one, it's a bit over
my head I'm afraid.
I understand that 8 disks is not optimal for a raidz set, especially for
random inputs, and your blog entry is the reason for my comment to that
effect near the bottom of my first post.
My lastest raid 50 results were much more healthy, but I don't know that
I'm ready to sacrifice 300GB of storage to that slight improve -
especially as zfs can't grow the individual stripes (yet...)
>
> I think that 5 disks for a raidz is the sweet spot
> IMHO. But ... YMMV etc.etc.
>
> FWIW: here's a datapoint from a dirty raidz system
> with 8Gb of RAM & 5 *
> 300Gb SATA disks:
>
> Version 1.03 ------Sequential Output------
> --Sequential Input- --Random-
> -Per Chr- --Block-- -Rewrite-
> -Per Chr- --Block-- --Seeks--
> Machine Size K/sec %CP K/sec %CP K/sec %CP
> K/sec %CP K/sec %CP /sec %CP
> zfs0 16G 88937 99 195973 47 95536 29
> 75279 95 228022 27 433.9 1
> ------Sequential Create------
> --------Random Create--------
> -Create-- --Read--- -Delete--
> -Create-- --Read--- -Delete--
> files /sec %CP /sec %CP /sec %CP
> /sec %CP /sec %CP /sec %CP
> 16 31812 99 +++++ +++ +++++ +++ 28761
> 99 +++++ +++ +++++ +++
> s0,16G,88937,99,195973,47,95536,29,75279,95,228022,27,
> 433.9,1,16,31812,99,+++++,+++,+++++,+++,28761,99,+++++
> ,+++,+++++,+++
Here is my version with 5 disks in a single raidz:
-------Sequential Output-------- ---Sequential Input--
--Random--
-Per Char- --Block--- -Rewrite-- -Per Char- --Block---
--Seeks---
Machine MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU
/sec %CPU
5 disks 16384 62466 72.5 133768 28.0 97698 21.7 66504 88.1 241481 20.7
118.2 1.4
Ouch, your one is much better! Can you tell me more about your setup?
> I'm *very* pleased with the current release of ZFS.
> That being said, ZFS
> an be frustrating at times. Occasionally it'll issue
> in excess of 1k I/O
> ops a Second (IOPS) and you'll say "holy snit, look
> at..." - and then
> there are times you wonder why it won't issue more
> that ~250 IOPS. But,
> for a Rev 1 filesystem, with the technical complexity
> of ZFS, this level
> of performance is excellent IMHO and I expect that
> all kinds of
> improvements will continue to be made on the code
> over time.
I don't really have a point of comparison to know how well my hardware
should be performing in the real world, just a gut feeling that it
should be doing better, and some rather odd scaling issues.
Please don't take this as zfs bashing. I still can't stop telling
everyone I know about how I can create a 2TB raid in 3 seconds - I think
ZFS is wicked cool!
This thread is two fold, 1) I'm hoping to learn more about the zfs &
solaris performance tuning by digging on in and investigating. 2) I have
some notion of hopefully being helpful by providing developers with some
real world data that might help in improving the code. I'm more then
happy to to any testing that anyone can throw at me. I've already had
one email from one person asking me to run their dtrace script with
benchmarking and email back the results.
This is great. I can't code, but if I can help give back in any way here
- hurrah!
> Jonathan - I expect the answer to your performance
> expectations is that
> ZFS is-what-it-is at the moment.
Along those lines, I'll upgrade to the lastest nevada as soon as my
connection finishes it. 5 CDs is very non-trivial down in this part of
the world sadly.
> Regards,
>
> Al Hopper Logical Approach Inc, Plano, TX.
Thanks for the reply Al,
Jonathan Wheeler
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