On Thu, 19 Sep 2002, SUBSCRIBE NETWORKER Anonymous wrote:

> Subject: [Networker] NetApp Backup
>
> Dear Networkers,
>
> I was wondering if any of you guys were using Legato for backing up your
> Network Appliance boxes. I currently have 2 filers that i am backing up
> to
> a Legato server running Solaris 2.8 over NFS. I mount the NetApp volumes
> onto the legato server and then backup those mount points.
>
> I am not sure this is the best thing to do in terms of performance.
>

We have two NetApps and are using NDMP to dump our NetApps to locally attached
drives.  There are pros and cons to using NDMP and I will summarize them
briefly.  Note that the problems are due primarily to the limitations of the
NDMP protocol and not to lack of features with Legato or NetApp.

Advantages:

  Performance
    With locally attached drives, performance generally increases unless
    you have a fast, dedicated network between your filer and backup server.
    Reading over NFS is likely to create a performance hit as well.
  Point-in-time dumps
    The filer makes a snapshot and writes the snapshot to tape, thus ensuring
    a clean point-in-time representation of your files.

Disadvantages:

  Loss of Legato-like feature with NDMP
    NDMP dumps essentially use the old unix "dump" semantics.  You therefore
    lose the following Legato functionality:
      - no incr dumps, just level 0-9
      - nwrecover indexes for a given browse time only contain files which
        were written to tape on the previous backup
      - can only recover 10,240 files with GUI/recover command
  Performance
    Target sessions per tape drive is limited to 1, thus it requires faster
    NetApps to be able to keep a single tape drive writing a maximum speed.

My complaint to NetApp about broken restores (bugid 76695) has been fixed.

My recommendation is to use a combination of filer snapshots for by-file
recovers and rely on tape backups for disaster recovery.

That is my little soapbox for NDMP vs nonNDMP dumps.  Feel free to jump in and
add to the foray!

Shelley

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