From: jmfres11@ucs.usl.edu (Karthikeyan Gurnswamy)
Subject: Re: multiple servers
Organization: Univ. of Southwestern La., Lafayette
Date: Thu, 3 Sep 1992 16:52:17 GMT

In article <9209021103.AA24686@lfkw2.bgm.link.com> Novell LAN Interest Group <NOVELL@SUVM.BITNET> writes:
>> >In bit.listserv.novell you write:
>>
>> >>What is the "best"way of implementing multiple servers?  I have about 400
> user
>> >>who want to use the same apps.  Is it better to duplicate apps on each
> server
>> >>or have everyone attach to one server.  This seems like it would get a bit
> hai
>> >>trying to keep accounts straight (which server gets the users home account).
>> >>A related question is Can redundancy be built into the two servers so if one
>>                            ^^^^^^^^^^
>>
>> We have for several years used a product called LANShadow from Netwave Inc. in
>> NYC (212 242-3200).  To quote from the manual: "LANShadow allows you to
> create,
>I've heard of LANShadow before, I'll give them a call.  I still have that basic
> question of what is the "best" way to set up multiple servers (mirroring
> aside).
>I guess I am looking for the all the options and see which would work for me.
> Does everyone log into one server and attach to the other, or log into both or
> just keep both servers identical except for user accounts.  This is assuming of
> course that all users want access to the same apps and utilities.
>
>thanks for any real life setups.
>
>
><- - - - - - - - - - - - - - - - - - - - - - - - - - - - - ->
>  Duane Kerstetter
>  System Administrator
>  CAE-Link
>  Binghamton, NY
>  u2d65@lfkw2.bgm.link.com
><- - - - - - - - - - - - - - - - - - - - - - - - - - - - - ->

Just recalling an article about Fault Tolerance in LAN Magazine two  
year back. The best way to get SFT LVL III ( Oops ! 2.99) is to do
workstation mirroring. You just have to run a special TSR on workstations
which duplicates read/writes and all the essential I/O to two drives
simultaneously. If these two drives are mapped to two different servers
and if the TSR can detect and handle drive crash then you get something
which is the best. Of course that includes multiple drive mirroring also.

Summarising the advantages:
(a) Servers can be of different types. Say a mix of SFT 2.15 and 3.11
(b) Server configuration can be different
(c) Easy to use and less complicated
(d) Only requires a TSR - no special hardware or installation
(e) Software gives you flexibility - Easy to mirror a server drive
    and local hard-disk !

The major disadvantage with workstation mirroring:
(a) If it can mirror drives, then software which uses Netware file names
    like SYS:PUBLIC/.. will go unnoticed by the TSR !
(b) Takes a little bit of memory which can be crucial to applications

The point is you don't have to waste a workstation to copy files which
has the following additional drawbacks:
(a) It is not real-time. What if the server blows when the copying
    cycle is half-way ? 
(b) It does not copy locked files which is the most crucial issue
    because most online applications use sharable and locked files !

P.S: Can someone update the workstation mirroring product list ?

Karthik
/----------------------------------------\--------------------------\
| Karthikeyan Guruswamy                  | I survived hurricane     |
| Graduate Student, Computer Science     |                          |
| Center for Advanced Computer Studies   |    ANDREW ...            | 
| Univ. of SouthWestern Louisiana        |                          |
| Lafayette, LA 70501                    |                          |
| Email: jmfres11@ucs.usl.edu            |                          |
|                                        \--------------------------\
| The opinions stated are solely mine and does not reflect the views|
| of anyone in my organization ...                                  |
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