Conference cpdev::lotus_notes

231.0. "Notes network bandwidth utilization" by ACISS2::DATZMAN (Vee Vont To Pomp You Up) Wed Apr 16 1997 11:07

    I have a customer that is trying to determine the network impact of
    adding Lotus Notes to their environment.  Listed  below is a customer
    memo that describes some network utilizations.  They have asked for
    comments and a sanity check.
    
    Thanks,
    
    dick
    
    
    ------------------------------
    
    
    IBM/Advantis "Rules of Thumb":
    It takes a T1 line to connect 750 users to a geoplex.  (We need to
    verify 
    this number! See notes on "active users" below.)
    
    In a separate conversation with Robert Larson-Hughes, Frank D'Aprise of 
    IBM offered the following formulas:
    Average Notes traffic generated by a proactive user = 3.6kbps
    (Wan link size * .6) / 3.6kbps = number of users a link can support.
    
    Reality check -- My math may not be the greatest, but I'd work it out
    like 
    this:
    
    1.544mbps x 1024 = 1581.056 kbps      This is the theoretical capacity
    of 
    a T1 line.
    1581.056 x .6 = 948.6336 kbps              This is the actual capacity
    of 
    a T1 line.
    948.6336kbps / 3.6kbps = 263.5           Number of users supportable on
    a 
    T1 line.
    
    
    Only 1/3 of users will be "active" at any given time. 
    
    If Advantis is connecting 750 users per T1, they must be using this
    rule.
    
    Assume bandwidth demands will increase due to attachments, heavier use, 
    etc.
    
    Advantis experience with SP2 servers suggests that Notesbench rating 
    should be decreased by 2/3 to get the actual number of users
    supportable 
    by the machine.  They had machines rated at 1500, found actual use was 
    closer to 1000.
    
    
    Suggested Customer metrics:  
    Concurrent users = "Active" users = Number of users at a site * .33
    
    Server capacity = Notesbench rating * .5
    
    WAN bandwidth requirement = 3.6kbps per active user.
    
    Using these metrics, the following model is conceivable:
    
    
    
    Active Users at each site = (750 * .33) = 250
    Server capacity = (1500 * .5) = 750
    Each T1 link can handle 250 concurrent users.
    
    Conclusion:  A server with a Notesbench of 1500 could conceivably
    support 
    2250 users.
    
    I'll feel a lot better when we have some experience to validate this.  
    Throw rocks at it.  What's missing?
    
    ----------------------

I suggest you call Harry Murray to get some empirical data on network
utilization on Notes.  He did a simulation study for a large customer 
who had specific network requirements, large attachments, and wanted to
correlate network load with Notes workload chanages.