VSP Gx00 Cache Status Test

The Hitachi VSP(Virtual Storage Platform) places all read and write data in the cache. The amount of fast-write data in cache is dynamically managed by the cache control algorithms to provide the optimum amount of read and write cache, depending on the workload read and write I/O characteristics. The Hitachi VSP is designed so that it cannot lose data or configuration information from the cache if the power fails. The cache is protected from data loss up for up to ten minutes by the cache destage batteries while the data is copied to the cache SSD (flash memory) on the cache boards. The cache may lose data due to reasons such as frequent power failure, corruption of the cache, memory overflow of the cache etc. To avoid such loss of data from the cache, it is necessary to keep track on the status of the cache and if errors are detected, administrators should identify the criticality of such errors! The VSP Gx00 Cache Status test helps administrators to keep a vigil on the cache!

This test reports whether the cache used by each RAID store on the storage device is currently experiencing any errors, and if so, how critical the error is.

Target of the test : A Hitachi VSP Gx00 Series storage device

Agent deploying the test : An external agent

Outputs of the test : One set of results for every RAID store on the Hitachi VSP Gx 00 Series device monitored

Configurable parameters for the test
  1. TEST PERIOD - How often should the test be executed
  2. Host – The host for which the test is to be configured.
  3. PRIMARY CONTROLLER IP - Specify the IP address of the storage controller on the target storage device in the PRIMARY CONTROLLER IP text box. By default, the IP address of the HOST will be displayed in the PRIMARY CONTROLLER IP text box.
  4. SECONDARY CONTROLLER IP - By default, the SECONDARY CONTROLLER IP text box is set to none. This implies that by default, the storage device being monitored supports a single controller only. Sometimes, a storage device could be configured with two controllers i.e., say for e.g., controller 1 and controller 2, so as to provide fail-over services - in other words, if the controller 1is down, then the controller 2 will take over to provide the critical storage services. In this case, you can provide the IP address of the controller 2 in the SECONDARY CONTROLLER IP text box.
  5. SnmpPortThe port through which the storage device exposes its SNMP MIB; the default is 161.
  6. SNMPVERSION– By default, the eG agent supports SNMP version 1. Accordingly, the default selection in the snmpversionlist is v1. However, if a different SNMP framework is in use in your environment, say SNMP v2 or v3, then select the corresponding option from this list.
  7. SNMPCommunity – The SNMP community name that the test uses to communicate with the firewall. This parameter is specific to SNMP v1 and v2 only. Therefore, if the snmpversionchosen is v3, then this parameter will not appear.
  8. username– This parameter appears only when v3 is selected as the snmpversion. SNMP version 3 (SNMPv3) is an extensible SNMP Framework which supplements the SNMPv2 Framework, by additionally supporting message security, access control, and remote SNMP configuration capabilities. To extract performance statistics from the MIB using the highly secure SNMP v3 protocol, the eG agent has to be configured with the required access privileges – in other words, the eG agent should connect to the MIB using the credentials of a user with access permissions to be MIB. Therefore, specify the name of such a user against the username parameter. 
  9. CONTEXT – This parameter appears only when v3 is selected as the SNMPVERSION. An SNMP context is a collection of management information accessible by an SNMP entity. An item of management information may exist in more than one context and an SNMP entity potentially has access to many contexts. A context is identified by the SNMPEngineID value of the entity hosting the management information (also called a contextEngineID) and a context name that identifies the specific context (also called a contextName). If the USERNAME provided is associated with a context name, then the eG agent will be able to poll the MIB and collect metrics only if it is configured with the context name as well. In such cases therefore, specify the context name of the USERNAME in the CONTEXT text box.  By default, this parameter is set to none.

  10. authpass– Specify the password that corresponds to the above-mentioned username. This parameter once again appears only if the snmpversion selected is v3.
  11. confirm password– Confirm the authpass by retyping it here.
  12. authtype– This parameter too appears only if v3 is selected as the snmpversion. From the authtypelist box, choose the authentication algorithm using which SNMP v3 converts the specified username and password into a 32-bit format to ensure security of SNMP transactions. You can choose between the following options:

    • md5 – Message Digest Algorithm
    • sha – Secure Hash Algorithm
  13. encryptflag– This flag appears only when v3 is selected as the snmpversion. By default, the eG agent does not encrypt SNMP requests. Accordingly, the encryptflagis set to no by default. To ensure that SNMP requests sent by the eG agent are encrypted, select the yes option. 
  14. encrypttype– If the encryptflagis set to yes, then you will have to mention the encryption type by selecting an option from the encrypttypelist. SNMP v3 supports the following encryption types:

    • des – Data Encryption Standard
    • AES – Advanced Encryption Standard
  15. encryptpassword– Specify the encryption password here.
  16. confirm password– Confirm the encryption password by retyping it here.
  17. TIMEOUT - Specify the duration (in seconds) within which the SNMP query executed by this test should time out in the TIMEOUT text box. The default is 10 seconds.
  18. DATA OVER TCP – By default, in an IT environment, all data transmission occurs over UDP. Some environments however, may be specifically configured to offload a fraction of the data traffic – for instance, certain types of data traffic or traffic pertaining to specific components – to other protocols like TCP, so as to prevent UDP overloads. In such environments, you can instruct the eG agent to conduct the SNMP data traffic related to the monitored target over TCP (and not UDP). For this, set the data over tcp flag to Yes. By default, this flag is set to No.
Measures made by the test:
Measurement Description Measurement Unit Interpretation

Cache status:

Indicates the current status of the cache used by this RAID store.

 

The values reported by this measure and its numeric equivalents are mentioned in the table below:

Measure value

Numeric Value

noError

1

acuteError

2

seriousError

3

moderateError

4

serviceError

5

Note:

By default, this measure reports the Measure Values listed in the table above to indicate the current state of the cache used by this RAID store. The graph of this measure however, represents the status of a server using the numeric equivalents only i.e., 1 to 5.