8. ANEXOS
8.12. Antecedentes de proyecto atención primaria de salud
There is a significant difference between displaying the channel failures and performing LAVe failure analysis. This diJf<:rence is shown in F igure 2, which represents a multiple-adapter LAVe conJiguration. ETHERNET LAN SEGMENT A
ETHERNET BRIDGE KEY:
I
TERMINATOR - TRANSCEIVER I ETHERNET I I ETHERNET I I ADAPTER 1 I 1 ADAPTER 1 I I _ _ _ _ _ _ I I _ _ _ _ _ _ I VAX A VAX B .- - - -, .- - - -. I ETHERNET I I ETHERNET I I ADAPTER 2 I I ADAPTER 2 IETHERNET LAN SEGMENT B
Figure 1 Network Delay Detection
New Availability Features of Local Area VAX cluster Systems
ETHERNET LAN SEGMENT A
DELNI A DELNI B
I ETHERNET I I ETHERNET I I ETHERNET I I ETHERNET I I ADAPTER 1 I I ADAPTER 1 I I ADAPTER 1 I I ADAPTER 1 I I _ _ _ _ _ _ I I _ _ _ _ _ _ I I _ _ _ _ _ _ I I _ _ _ _ _ _ I
ETHERNET VAX A VAX B VAX C VAX D
BRIDGE
,- - - -. .... - - - -. .- - - -. ,... - - - -. I ETHERNET I I ETHERNET I I ETHERNET I I ETHERNET I
I ADAPTER 2 I I ADAPTER 2 I I ADAPTER 2 I I ADAPTER 2 I
DELNI C DELNI D
ETHERNET LAN SEGMENT B
KEY:
I
TERMINATOR - TRANSCEIVERFigure 2 Multiple-adapter Channel Failure Looking from system VAX A, the fol lowing chan
nels exist: A l -A2, A2-Al, A l -B l , Al -B2, A2-Bl , A2-B2, A l -C l , A l -C2, A2-C l , A2-C2, A l - D l , A 1 -D2, A2- D l , and A2-D2. let us assume that DELNI B fails, causing the following channel failures: A l - C l , A2-Cl , A l - D l , and A2- D l . A display of channel failures wou ld show that some interesting event had just occurred but would leave it up to the system or network manager to isolate the actual failure. Also, since other channels are still open to VAX C and VAX D (Al -C2, A2-C2, A l -D2, and A2-D2), these nodes still remain in the cluster. However, the number of channels to these nodes has been halved, reducing cluster availability.
LAVe network failure analysis uses the physical network description to analyze channel failures. The working channel A l -C2 indicates that VAX A, A I , DELNI A, LAN segment A, Ethernet-to-Ethernet LAN bridge, LAN segment B, DELNI D, C2, and VAX C function. The working channel A2-D2 indicates that A2, DELNI C, 02, and VAX D also function. The remaining components are DELNI B, C l , and 0 1 . By reviewing the failing channels for common failures, we see that two channels use component C l , two channels use component D l , and all fou r channels use component DELNI B. Therefore, DELNI B has the highest probability of causing the failure and is the only network component displayed on the console.
Digital Tech11icaljournal Vol. 3 No. 3 Summer 1991
In this small cluster configuration, LAVe network failure analysis has reduced the messages displayed, i.e., from four channel failure messages to one component failure message. This simpler display provides timely notification and better isolation of network component failures, allowing the system or network manager to repair the network earlier and restore the full availability of the cluster.
Physical Network Description
LAVe network failure analysis requires a description
of the physical network. This description lists the components used by the LAVe and the network paths that correspond to the LAVe channels.
The network component description consists of several pieces of data, including a component type and text description provided by the system or network manager. Some component types will require additional data. There are several types of network components: NODE, ADAPTER, COMPO NENT, and CLOUD. Each NODE component requires a u nique node name associated with it that matches the SCSNODE SYSGEN parameter. The ADAPTER com ponent has at least one and sometimes two LAN addresses associated with it. One LAN address is the hardware address and the other, when specified, is the DECnet LAN address. COMPONENTs are used to describe all pieces of the network, both working
Availability in VAXcluster Systems
and nonworking. CLOUDs describe portions of the network that are working only if all paths are work ing. Any path failure impl ies that the CLOUD com ponent may not be working.
Component descriptions can range from actual devices and cables to internal CPL bus adapters. When the component is defined, an ID value is returned for use in the network path description. The choice of the components dcscrihcd is left to the system or network manager and a l lows the manager to select the desired level of network anal ysis. Each network component has a reference count and a working count. The reference count is incremented when a network path is defined that utilizes the network component. The working count is incremented each time a LAVe channel is opened, and decremented each time an open LAVe channel is closed.
The network path description consists of a d i rected list of component identifier (ID) values. For proper analysis, this l ist must start with the I D value for the local node. Each successive I D value i n the l ist must b e associated with the next network component through which a message would travel when using this path . The final component ID va lue is that of the remote node.
Each network path description must contain two node ID values and two adapter ID val ues. '{(> be use ful for analysis, the path description must contain the node ID value for the node running the analysis. Without this node JD value, the path cannot be matched with any of the LAVe channels on that node.