Date: Fri, 18 Sep 1998 16:18:27 -0700 From: Jeff Gray <jwg@cm110119.cableco-op.com> To: brian@worldcontrol.com Cc: freebsd-questions@FreeBSD.ORG Subject: Re: Root Disk Backup. Message-ID: <19980918161827.65051@cm110119.cableco-op.com> In-Reply-To: <19980918124926.A1848@top.worldcontrol.com>; from brian@worldcontrol.com on Fri, Sep 18, 1998 at 12:49:26PM -0700 References: <36029DED.100E0A16@open.org> <19980918124926.A1848@top.worldcontrol.com>
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Hmm.. why not use rdist ?
-can be done without shutting down as it works even on
executing files.
from man rdist
Rdist is a program to maintain identical copies of files over multiple
hosts. It preserves the owner, group, mode, and mtime of files if possi-
ble and can update programs that are executing. Rdist reads commands
from distfile to direct the updating of files and/or directories.
I *think* rdist is available on both SCO and BSD. Runs over tcp/ip
jeff
On Fri, Sep 18, 1998 at 12:49:26PM -0700, brian@worldcontrol.com wrote:
> On 0, Robert Clark <Clark@open.org> wrote:
> > I'm trying to establish a set of tools that will minimize downtime when
> > a root disk fails.
> > Not because root disk failure is a frequent occurance, but when it
> > happens, its always a key system at a bad time.
>
> > Questions / assumptions:
> > FreeBSD can backup a HD even if their is no FS FreeBSD recognizes? (I've
> > worked with a few (non UNIX0 tools that need a (PC-style) partition
> > table to do their jobs.)
> > As long as the geometry of the replacement drive is the same, does this
> > approach sound feasible?
>
> yes. I do it all the time.
>
> > What commands / programs could I use under FreeBSD?
>
> cat /dev/rsd0 | gzip | > backupcopy
>
> > Is anyone else out there doing anything like this?
>
> Yes.
>
> > In order to keep the amount of time a station is down during root-disk
> > backups, I'm entertaining the idea of making the initial copy a disk to
> > disk process. (And dump the second disk to tape a few minutes later.) I
> > was hoping that disk to disk would be quite a bit faster than disk to
> > tape.
>
> Yes. Disk to Disk is far faster, and IMHO more reliable.
>
> > Compound Question: (More for info than for need.)
>
> > If you dump a binary image of said HD, compression won't do much. Even
> > if the HD is only 10% in use, the compression algorithm won't know what
> > is files, and what is deleted files.
>
> I generally get around 50% compression with gzip on the raw size of
> the disk. bzip2 is too slow because it doesn't like compressing large
> areas of similar data (blank sectors). A fully used filesystem might
> not have this problem.
>
> > Dumping a binary image of a "washed" disk would seem to be faster.
>
> I find copying a disk to disk runs at about a constant rate regardless
> of the data. The compression time can change.
>
> > Washed areas should be easier to compress.
>
> Yes gzip, No bzip2.
>
> --
> Brian Litzinger <brian@litzinger.com>
>
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