Panzura Cache Statistics Test

Panzura CloudFS utilizes a user-definable percentage of the local storage as the SmartCache to track hot, warm, and cold file block structures as they are accessed. This form of caching increases the I/O performance of reads by servicing them from local cached storage rather than from external cloud storage. Caching policies provide two basic functions. The first function is pinned data, which keeps data available on local storage using flexible wildcard policy rules. Pinning is a forced action and executed against full files whereas SmartCache is a read-stimulated action executed against frequently accessed blocks within a file. The second function provided by caching policies is Auto-Caching which automatically caches data locally based on defined rules. Auto-cached data can be evicted for requested hot data, as needed. The pinned, or auto-cached, data is a subset of the total SmartCache storage tier. Pinned data is considered high-priority cached data that is never evicted unless authorized by the administrator, whereas auto-cached (cached based on wildcard rules) or SmartCache cached (data blocks automatically cached based on observed usage patterns) can be evicted by the system if needed to make space for more frequently accessed data.

As more pinned data consumes the local space, the usable auto-cache capacity is reduced. This will negatively impact the most frequently read data, causing it to be evicted and then re-read continuously. Therefore, aggressive policies that pin large amounts of data should be used sparingly as this could cause excessive local disk I/O and reduce performance. Also, over consumption of local space by pinned data causes inefficient local cache utilization leading to less or no space for actual hot data. Therefore, it is imperative to keep an eye on the number of cache hits and misses of pinned, auto-cached and evicted data for ensuring efficient perfromance of the appliance. The Panzura Cache Statistics Test helps administrators in this regard!

This test monitors the local storage of the target appliance and reports the number of cache hits and misses with pinned and auto-cached data in the local cache. This way administratrors can easily identify when the amount of pinned data increases beyond the permissible limit over-riding the auto-cached data. This test also keeps a track on the number of cache misses, thereby shedding light on the unavailability of hot pinned or auto-cached data. In addition, this test also promptly alert administrator on the number of evictions from the local cache, thus helping them to proactively resolve any potential perfromance issues before it affects the user experience.

Target of the test : A Panzura Cloud file system

Agent deploying the test : An external agent

Outputs of the test : One set of results for the target appliance being monitored

Configurable parameters for the test
Parameters Description

Test period

How often should the test be executed

Host

The IP address of the host for which this test is to be configured.

SNMPPort

The port at which the monitored target exposes its SNMP MIB; the default is 161.

SNMPVersion

By default, the eG agent supports SNMP version 1. Accordingly, the default selection in the SNMPversion list 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.

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 SNMPVersion chosen is v3, then this parameter will not appear.

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 this parameter. 

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.

AuthPass

Specify the password that corresponds to the above-mentioned Username. This parameter once again appears only if the SNMPversion selected is v3.

Confirm Password

Confirm the AuthPass by retyping it here.

AuthType

This parameter too appears only if v3 is selected as the SNMPversion. From the AuthType list 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
  • SHA224 - Secure Hash Algorithm 224 bit
  • SHA256 - Secure Hash Algorithm 256 bit
  • SHA384 - Secure Hash Algorithm 384 bit
  • SHA512 - Secure Hash Algorithm 512 bit

EncryptFlag

This flag appears only when v3 is selected as the SNMPversion. By default, the eG agent does not encrypt SNMP requests. Accordingly, the this flag is set to No by default. To ensure that SNMP requests sent by the eG agent are encrypted, select the Yes option. 

EncryptType

If the EncryptFlag is set to Yes, then you will have to mention the encryption type by selecting an option from the EncryptType list. SNMP v3 supports the following encryption types:

  • DES - Data Encryption Standard
  • 3DES - Triple Data Encryption Standard
  • AES - Advanced Encryption Standard
  • AES128 - Advanced Encryption Standard 128 bit
  • AES192 - Advanced Encryption Standard 192 bit
  • AES256 - Advanced Encryption Standard 256 bit

EncryptPassword

Specify the encryption password here.

Confirm Password

Confirm the encryption password by retyping it here.

Timeout

Specify the duration (in seconds) within which the SNMP query executed by this test should time out in this text box. The default is 10 seconds.

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 this flag to Yes. By default, this flag is set to No.

EngineID

This parameter appears only when v3 is selected as the SNMPVersion. By default, the EngineID parameter is set to No. Administrators need to set this flag to Yes, only if they choose AES192 or AES256 as the Encryption type.
Measurements made by the test
Measurement Description Measurement Unit Interpretation

Data hits in auto cache

Indicates the number of times requests for auto-cached data were serviced during the last measurement period.

Number

 

Data hits in pinned data

Indicates the number of times requests for pinned data were serviced during the last measurement period.

Number

 

Data misses from auto cache

Indicates the number of times the local cache could not service the requests for auto-cached data during the last measurement period.

Number

Ideally, the value of this measure should be 0. A very high value is a cause for concern as it indicates ineffective utilization of local cache.

If the value of this measure is high, it is an indication of unavailability of auto-cached data. This might be due to over-consumption of cache space by high priority pinned data. This results in less or no space for actual hot data in the local cache.

Data misses from pinned data

Indicates the number of times the local cache could not service the requests for pinned data during the last measurement period.

Number

Ideally, the value of this measure should be 0. A very high value is a cause for concern as it indicates ineffective utilization of local cache.

If the value of this measure is high, it is an indication of the unavailability of high priority pinned data from the local cahe.

Data evicted from data cache

Indicates the number of data evictions from the local cache during the last measurement period.

Number