[Spread-users] Wackamole IP takeover time
Theo Schlossnagle
jesus at omniti.com
Sat Jul 13 21:50:52 EDT 2002
On Saturday, July 13, 2002, at 07:04 PM, Min Lu wrote:
> Thanks. That's what I was looking for "10-20 milliseconds to switch the
> virtual IPs".
> Is this recorded from lab test or is it an educated guess?
Educated guess. But I have seen take over times of less than then in
practice when a service fails (instead of a machine). As Yair said,
when a machine fails, the Spread daemon membership must take place
before the notifications will reach wackamole... So this could take
several seconds -- but it could be tuned to be much tighter than this.
> On another note, does anyone know if there is any open source
> disk mirror driver like DRDB for Solaris? Someone must have
> done it already since it is a popular platform. WE don't like Sun's
> commercial equivalent that costs $$$$.
I personally _really_ like the commercial volume manager for Solaris. I
assume you are speaking of the Veritas Volume Manager. I think the
Veritas suite of software storage facilities is unparalleled. I have
not seen a volume manager and filesystem combo that even approaches its
quality for standard UNIX environments -- free or commercial.
I am unaware of any open source volume management applications for
Solaris. If you are just talking about a kernel driver to mirror a disk
and do fail over, I would image that would be trivial to implement --
but it seems to only provide a little whereas something like VxVM + VxFS
provides everything you could ever want.
My two cents. :-D
Like most things. If you have an application that _requires_ the sort
of availability that can only be provided by such software tools,
chances are the price is not that substantial in that picture. On a
parallel, Sun Cluster does tons of stuff that wackamole will simply
never do -- if you truly _need_ Sun Cluster, chances are you can afford
it.
--
Theo Schlossnagle
Principal Consultant
OmniTI Computer Consulting, Inc. -- http://www.omniti.com/
Phone: +1 301 776 6376 Fax: +1 410 880 4879
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