Linux as a NAS performance questions

[H. Kurth Bemis]

On Thu, 2009-09-17 at 17:59 -0400, Alan Johnson wrote:
> On Thu, Sep 17, 2009 at 4:09 PM, Neil Joseph Schelly
> <neil at jenandneil.com> wrote:
>         I'm looking to build a small Shuttle barebone machine into a
>         NAS running
>         Linux.  The intent of the machine is to be a networked PC with
>         lots of
>         storage in a RAID array, made available over the gigabit
>         network interface
>         via Samba, NFS, and maybe iSCSI protocols.  I'm curious what
>         experience
>         others have with this sort of stuff in general, but two
>         immediate questions
>         come to mind about processor and memory performance.
>         
>         I can go the low-power, low-heat route and get a single-core
>         processor and a
>         single memory stick of minimal quantity.  Or I can upgrade a
>         bit, get a
>         dual-core processor with 2 sticks of dual-channel memory.  Or
>         something in
>         between.  What I don't know is how much impact processor
>         speed, multiple
>         cores, memory capacity, and dual-channel memory has on disk
>         I/O, network I/O,
>         software RAID processing, etc.
>         
>         I like the idea of a small low-power, low-heat appliance, but
>         will going too
>         low on those negatively impact performance much?  The cost
>         difference between
>         a single-core processor with 1GB of memory and a dual-core
>         processor with 2
>         sticks of 1GB dual-channel memory is insignificant, so that's
>         not much of a
>         concern.
>         -N
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>         gnhlug-discuss mailing list
>         gnhlug-discuss at mail.gnhlug.org
>         http://mail.gnhlug.org/mailman/listinfo/gnhlug-discuss/
> 
> Any modern processor will be bored for these services, even if you use
> an encrypted and compressed file system.  Single core will be plenty,
> but I don't know how much it will save you on power.  Focus first on
> low power design and then on number of cores.  You may find some
> multi-cores do better then some singles.  The Intel Atom is probably
> your best bet and should still have plenty of spare processing
> power.  
> OK, so MAYBE and Atom won't keep up with GigE if you use compression
> and encryption.  It probably depends on the compression and encryption
> algorithms. I don't really know, but I bet you will be fine.
> 
> Disk IO and then network are going to be your bottlenecks.  More RAM
> will help disk IO via the OS's disk cache depending on the usage
> patterns of the data store, but most NAS appliances only have a couple
> hundred MB if you are lucky.  If you are just using it for backups for
> steaming media, you can run very happily with as little as 64MB
> (assuming no GUI), but you may need more than that just to install the
> OS, depending on the distro.  Higher RPM on disks will of course help
> IO, but not the power consumption.  SSD will help both, but not your
> wallet.  I like the Western Digital Green drives for this purpose as
> the only spin at 5400 RPM when they can get away with it and jump to
> 7200 RPM when the demand requires it.  Compression will also help disk
> IO in most cases, and if you expect a lot of concurrent requests, play
> around with ionice on some of your NAS services.
> 
> BTW, you might want to check out the FreeNAS project.  From what I
> understand, there is nothing in there you can't get in another distro,
> but they keep it pretty lean while providing all the services you
> mentioned on a fresh install.  Don't take my word for it though.  It
> has been while since I looked into it.
> 
> Ubuntu Server does a very lean install as well.  Not quite as lean as
> Debian (and others), but even at the command line, I find Ubuntu is
> more friendly.  I think there might have been a file server option on
> the Jaunty Server installer, but I don't pay much attention to such
> things as I like to to a bare install on a Server and pick the packges
> I want myself.  Definitely a Samba option at install, but again, you
> might bet more than you need or want that way.  SSH is a good option
> at install.
> 
> You might also consider webmin if you are not hardcore on the command
> line.  It will ask you if you want to install the relevant packages if
> it can't find a service when you access the module, so it makes a nice
> add on to a bare Ubuntu Server install.  To install, use "dpkg -i
> webmin*.deb" then do an "apt-get -f install" when dpkg fails and
> apt-get will go fetch the dependancies and finish up the webmin
> install.  Once webmin is running, you need not the command line any
> more.
> 
> I have also heard very good things about ebox (Ubuntu only last I
> knew) but I have not been able to access it on my home server yet
> because the browser is puking on the cert for some reason and I have
> not cared to fight with it yet.
> 
> That's my $1.37 (2 cents with inflation).
> 
> -- 
> Alan Johnson
> alan at datdec.com
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> gnhlug-discuss at mail.gnhlug.org
> http://mail.gnhlug.org/mailman/listinfo/gnhlug-discuss/

I've been working on a similar project.  Simply put, a low-power PC,
running linux/BSD with oodles of storage for my torrents and ever
growing media collection.

Take a look at LogicSupply (logicsupply.com).  They have a pretty good
selection of compact systems.  Atom based systems too.

I second FreeNAS.  Very slick little distro. (Is it a distro or what?)

~k

(Alan - I knew you had to get a plug for webmin in somewhere! :])