ITEM: RTA000027792

I am in the process of putting together a high availability                     
solution for a customer.  Please read the following                             
proposed solution and address the questions I have after                        
The configuration is to have two RISC/6000's configured in                      
a mode 2 HACMP setup.  The first RISC will be  a 980 with                       
14 GB of 1.07 GB serial drives.  I will max out the driver                      
drawers in the base 980 rack, then add a 7202-900 and put                       
the additional disks in the drawers there.  This 980 will                       
have 4 64 port adapters to start. It will also have the                         
optical serial link and dual ethernet cards.  The                               
application running on this 980 will be the Advanced Pick                      
database (from Pick Systems).  This application writes to a                     
raw logical volume and bypasses the standard JFS                                
The other RISC/6000 is a model 580.  This will have 4 64                        
port adapters with no concentrators attached.  In the case                      
of the 980 failing, the system operator will detach the                         
concentrators from the 980 64 port adapters and just plug                       
the concentrators into the model 580 64 port adapters.                          
This 580 will be running Netware for AIX.  The Netware                          
clients will be attached across the dual ethernet cards                         
which will also be attached to the 980.  The 580 will have                      
a serial optical connection to the 980.  The 580 will also                      
be connected to the 1.07 GB serial drives which make up the                     
14GB I described in the 980 config above.                                      
I would like the 580 to 'backup' the 980 and it's Pick                          
application with ascii terminals.  I would like the 980 to                      
'backup' the 580 and it's Netware/6000 application with                         
ethernet attached clients.  I would like to set this whole                      
thing up using the hacmp product.  It looks pretty possible                     
so far, but I do have some concerns and questions.                              
My questions are as follows:                                                    
1)    Please comment on the feasability of this solution.                       
      Specifically address:                                                     
       A)  whether Netware/6000 will be able to work in/and                     
       take advantage of an hacmp configuration.                                
       B)  whether the 580 can attach to the serial disk in                    
       both the 7202-900 as well as the disk drawers in the                     
       base 980 rack                                                            
       C)  whether just simply swapping the 64port                              
       controller concentrators is the best solution, or                        
       would terminal servers be better?  Why?                                  
       D)  any other issues you see here that I should be                       
       aware of?                                                                
2)    A)  In an HACMP solution, when the 'failover' process                     
occurs what happens to the data that is in memory?  (I call                     
this 'sync level data' for lack of a better term)                               
      B)  Is there any way of protecting this data?  Or at                      
least tracking (journaling) what data is there so that when                     
the switchover to the new machine occurs, my customer can                       
be sure of the integrity of their data? (ideally this would                    
occur independent of the application)                                           
      C)  What happens to this 'sync level data' in a disk                      
mirror take over in the event of a disk crash?                                  
3)    Do all of the disk drives need to be attached to                          
single serial subsystem adapter?  In other words, if I had                      
2 serial subsystem adapters in the 980, each attached to 8                      
drives... could the 580 have a single subsystem adapter                         
which would attach to all 16 drives?                                            
4)    Is there an optimum serial cable length for both the                      
serial optical channel as well as the serial disks?  (the                       
configurator provides many lengths so could you please                          
explain and comment on this... then make recommendations)                       
5)    Does the 980 support AIX windows across a network?                        
(attaching an Xterminal or XONDOS based pc to the ethernet                      
adapter for example)                                                            
6)    What are the cable choices for the hacmp serial link                      
(heartbeat)?  Optical serial, copper (8-wire rs232) serial,                     
7)    Can the 580 come with a serial disk select like the                       
980 has so that ALL disk on the system is serial disk?                          
8)    In the event we do go with terminal servers rather                        
than ascii controllers....                                                      
       A)  What are the practical telnet limitations on an                      
       ethernet card (before congestion or whatever else                       
       becomes a problem)                                                       
       B)  does rlogin support transfer of emulation?                           
       Their terminals are addsvp and are limited to tvi925                     
       emulation only˘  (so telnet being limited to vt100                       
       or vt220 is almost out of the question...maybe                           
       rlogin provides a workaround so that risc/220's                          
       could be used as terminal servers)                                       
       C)  What are the practical rlogin limitations on an                      
       ethernet card (before congestion or whatever else                        
       becomes a problem)                                                       
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A:     I will answer your questions in the order that you asked them.           
    1.  a)  Netware/6000 can run with HACMP/6000, however, whenever            
  HACMP does an adapter swap, IP-address takeover, or when a failed             
  machine is brought back online, NETWARE/6000 will get clobbered and           
  have to be restarted.                                                         
        b)  Yes, you can attach the serial disks to both the 980 and            
  the 580 RISC System/6000 machines.                                            
        c)  Both of these methods will work fine.  However, if you get          
  a terminal server, i.e. 220 or 3XX machine, and have this server all          
  of the incoming terminals, it will be able to automatically switch to         
  the backup server.  This is because the terminal server runs a HACMP          
  program called clinfo.  This program keeps track of the cluster state         
  and does certain tasks accordingly.  These tasks are manually                 
  made by the user.                                                             
        d)  There are a couple of issues that you may want to consider.         
  The Serial Optical Channel Converter (SOCC) is not required by HACMP          
  and is not usually recommended unless the SOCC network is going to be         
  used for other private stuff between the two systems.  To use SOCC just       
  for the heartbeat is considered to be overkill.  HACMP/6000 now               
  requires that there is a raw RS-232 line connected between the two            
  machines.  This RS-232 line is used to guard against TCP/IP failure on        
  one of the machines causing a failover to automatically occur.                
    2.  a)  When a failover occurs, all of the data in memory that has          
  not been synced will be lost.                                                 
        b)  Since there is no way to determine when a failure is going to       
  occur, there is not any way to completely record what is in memory.  A        
  way to improve recovery of this data is to have the system sync more.        
  Or you can also be sure that a sync is done after every transaction.          
  This however will not completely guard against memory data loss.              
        c)  I the event of a disk crash and having a mirror takeover, the       
  data in memory will still be there.  Since the system will still be up        
  and active.  Mirroring takeover is done on an LVM level and will not          
  affect the data in memory.  When the sync is done, the data will be           
  written to the good copies of the logical volume.                             
    3.  No, all of the disk drives do not need to be connected to a             
  single serial subsystem adapter.  As long as all 16 drives will reside        
  within 4 drawers, there is not any problems with putting them all on          
  a single adapter.                                                             
    4.  No, there is not an optimum serial cable for either the SOCC or        
  the serial link cables.  The SOCC will be dependent on how far apart          
  the 980 is from the 580.  Probably, since there will be a 7202 between        
  them, you will need to have at least a 10m cable.  But again, this will       
  be dependent on how far apart you systems are.  For the serial link           
  cables, it will be dependent on whether you will be going from a system       
  to a drawer within the system rack, or if you are going between a             
  system and a drawer in an external rack.  Going from the 980 to 9333's        
  within it own rack, you will only need a 3m cable.  But going from the        
  980 to the 9333's within the 7202 will require a 10m cable.                   
    5.  Yes, you can support AIX windows across the network.  The only          
  restriction with the 980 is that it does not support an HFT (graphic          
    6.  The heartbeat will go across all defined networks.  For the raw        
  RS-232 line you will need to have the following:                              
        a.  Printer/Terminal Interposer                                         
        b.  10-pin to 25-pin Jumper                                             
        c.  3m EIA-232 cable (25-pin on both ends)                              
        d.  Serial Gender Changer                                               
    7.  No, according to the Salesmanual, the serial disk select                
  is not an option for the 580 RISC System/6000.                                
    8.  a)  The practical telnet limitation will be dependent on what you       
  are running across that telnet session.  What I suggest is that you           
  start up one average telnet session that you will be using.  Then use         
  netstat to determine how much of the ethernet that one telnet session         
  is taking up.  Saturation usually occurs at 70-80 percent of the              
  bandwidth.  So use the netstat information to determine what the point       
  of congestion will be.                                                        
        b)  We have not heard of any terminal limitations with either           
  telnet or rlogin.  When either of these are started up, there should          
  be an arbitration for the terminal type and if the term type is known         
  to the system that you are logging in to, it should be set to that            
  terminal.  The tvi925 emulation is know to the AIX 3.2 machines and           
  should not be a problem.  This emulation is located in the televideo.ti       
  file in the /lib/terminfo directory.                                          
        c)  Determining this is the same as with telnet.  It is hard to         
  know what the number of rlogin sessions there can be before saturation        
  of the network.                                                               
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This item was created from library item Q612901      BWQRT                      
Additional search words:                                                        
RISCSYSTEM SOFTWARE SYS                                                         

WWQA: ITEM: RTA000027792 ITEM: RTA000027792
Dated: 11/1996 Category: RISCOSO
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