[Summary] NAS or Direct-attached Storage

From: Please Sun <sunsolve_at_hotmail.com>
Date: Wed Sep 11 2002 - 06:36:05 EDT
Hello Admin,

	Thanks for your reply ..

<<< Question >>>

     We consider to purchase a storage to increase disk
     capacity and performance on our unix  environment,
     i.e Solaris and Redhat Linux.

     We have three options:
     1) NAS - Netapp 810
     2) NAS - EMC IP4700
     3) Direct-attached - Sun 280R + EMC FC4700

     My question is,
     1) Is NAS storage suitable for Pure UNIX
     2) Can NAS storage have any issue for
        a) Symbolic link
        b) ufsdump and ufsrestore
     3) Netapp 810 Vs EMC IP4700
     4) NAS Vs Direct-attached
     5) Any other issue I need to consider

<<< From: Uwe Weber >>>
     <1>  Since the NAS-box acts as an NFS-server,
          it's of course suitable in an UNIX Environement.
     <2a> Same as with any other NFS-Server.
     <3b> Ther is no use in ufsdumping NFS mounts. Depending
          on your backup strategy and tools either use your
          backup tools agent for Netapp (if it's got one)
          or the NetApp supplied tools on the filer.
     <3>  There have been issues regarding the Clariions 4700.
          Do a search on comp.arch.storage and visit
          gunbrowker.com. They had severe data losses because
          of problems with their Clariions.
     <4>  Most of the time, NAS is much easier to administer.
          NetApp NAS will be more expensive in hardware and
          maintenance fees than DAS. You should analyze how
          much you 're going to save in administration costs
          and storage related  downtime through using NAS.
     <5>  If going for a Clariion (or any other FC-based
          solution), do you have people trained to work with
          the FC stuff? If not, stick with NAS, almost any
          admin knows how to work with fileshares over
          ether + ip.
     <o>  You might want to have a look at HDS Thunder
          storage combined with microstore NAS.

<<< From: Sean Quaint >>>
     I've worked with NetApp and Procom.  Check out the
     NetForce1750.  I think they are easier to admin and
     just as effective for the money. Plus, they are wicked
     fast. NAS does work well with Unix.  You will not be
     able to use ufsdump, however, since ufsdump does not
     backup NFS mounted file systems.  So, you'll have to
     use tar or cpio if you want to use standard tools.
     NetBackup works well with NAS devices, however, you'll
     hae to purchase either NetBackup Datacenter if you want
     to backup the NAS via NFS, or the NDMP module if you
     want to back it up to a directly attached tape drive.

<<< From: Christophe Dupre >>>
     my take on this... NAS is almost always a so-so idea,
     especially if the data provided by the NAS is for one
     or a small number of servers. In this case, you're
     adding another source of problem (network switch) for
     small benefits. However, if you're exporting the data
     to a large number of machines, NAS can make sense
     (but is usually more expense than server+attached

     directly-atached storage is good for small storage
     (i.e. 20GB of mail data for example). It doesn't
     scale well.

     My favorite: SAN. A SAN is not that much more expensive
     than DAS, and usually less than a NAS. SAN gives you a
     lot of bandwidth with a very small overhead (compared to
     NAS). It also makes it easy to move data from one machine
     to another, or share it for recovery or backup purposes.

     I have no personnal experience with the two models of
     equipment below. NAS works good in a Unix environment.
     It looks as if an NFS server is on the oher side,
     so permissions, symlinks etc are kept. Backup however is
     often very slow.

<<< From: Scott Croft >>>
     We have been having extraordinary success with the NetApp
     and EMC is a pain to deal with.

<<< From: Paul Galjan >>>
     The IP4700 proved highly unstable in my NFSv3-only
     environment.  Two different machines crashed about 6 times
     in 8 months, the last time resulting in complete loss of
     data on one volume.  Do a search on "IP4700 Horror story"
     on groups.google.com for more details of my adventure.

     They've since replaced it with an FC4700, frontended by a
     single E220 I had laying around.  The jury is still out on
     its performance, but I've yet to get better than 15 MB/s
     from that setup.

     I like NAS in general, and I've heard good things about the
     NetApp. However, the EMC and NetApps are very expensive for
     what you get. Today's disk capacities allow greater than
     1TB in a traditional ~$10k SCSI enclosure.  Slap on Veritas
     or QFS, and you're fine.

     A big advantage DAS with a Sun frontend has is that I can
     upgrade the Sun host at will, with very little cost (compare
     upgrading a Netapp or IP4700 to gigabit ethernet to upgrading
     a single sun host with Gigabit ethernet).

     Two drawbacks:
     1. Scalability is limited to 2 TB unless you have a FC host.
     2. Hardware redundancy is harder to achieve; but keep in mind
        that hardware failure accounts for only 10% of downtime.

     You cannot use ufsdump with NAS, unless you've rolled your
     own with a Sun host.  Symlinks are part of NFS, so you
     shouldn't have a problem.

     If you're looking for a robust and scalable, but less
     expensive option to the NEtApp and FC4700, look at the
     LSI MetaStor or the SToragetek 9176.  Direct attach it to
     one or more Sun hosts, and put QFS or Veritas on it.

<<< From: Riddoch, John E >>>

     Well, we've used a variety of NAS stuff here, including:
     - Auspex
     - Sun + T3 storage
     - IBM + SSA storage

     In regards to your questions:
     1)  Yes, NAS is suitable for Unix, provided it's designed to
         handles NFS etc.
     2a) Symlinks work fine, again provided it's designed to
         handle Unix.
     2b) ufsdump likely won't work, so you'll have to find some
         other backup method.

     As far as direct attach vs NAS, NAS gives greater flexibility
     but less performance.  A SAN gives flexibility, but with the
     performance.  It's also more complex and probably more
     expensive to start off with.

<<< From: Chris Hoogendyk >>>
     we have had some major fights here over that question. no
     resolution as yet. money vaporized.

<<< From: Jeremy Jin >>>

     That depends on what OS the NAS uses. If the NAS runs a
     unix-like OS (for example, some NAS are actually linux box),
     then it would be totally compatible with pure unix environment,
     and no problem with symbolic link. But probably they don't use
     UFS, so ufsdump/ufsrestore won't work.  I have no knowledge
     with your other questions.

<<< From: Jay Lessert >>>
     1)  Sure.  NFS was *invented* for Unix, in Unix.
     2a) No.
     2b) NetApp does it's own dump and restore.  Don't know about EMC.
     3)  NetApp is faster in real life.
         NetApp is far easier to administer.
         NetApp is cheaper (last time I looked, over a year ago).
         NetApp snapshots are far more useful than EMC.
     4)  I don't understand.  If you only have one computer, than
         Direct-attached is probably fine.  If you have more than
         one computer, how can you not have NAS?

<<< From: Jeff Kennedy >>>
      We use NetApp 880 and 840 filers for our Unix environment,
      they work great.  I highly recommend them over EMC and
      direct attached.

Best regards,

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Received on Wed Sep 11 06:39:30 2002

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