Synology LUN Details Test

A LUN is a part of a volume segmented to provide storage for your hosts (initiator side) as a block device. Synology NAS supports two types of space allocation, Thick Provisioning and Thin Provisioning. With Thick Provisioning, the entire LUN capacity is pre-allocated on the volume from the moment a LUN is created. The LUN consumes all the space allocated to it on the volume, so the space is unavailable for use by other services. A Thin Provisioned LUN takes up actual used space and asks for more only when you write data to it. Poor utilization of LUNs or abnormal I/O activity on the LUNs, if not promptly detected and resolved, can significantly degrade the performance of the target Synology NAS storage system . This is why, it is important that LUN performance is continuously monitored. This can be achieved using the Synology LUN Details test.

This test auto-discovers the LUNs in the storage system and reports the rate at which data was read from and written to each LUN. In addition, this test also measures the level of I/O activity on every LUN. By closely analyzing the metrics, administrators are notified of LUN-related problems well before they impact storage system performance.

Target of the test : Synology NAS storage system

Agent deploying the test : An external agent

Outputs of the test : One set of the results for each disk on the target Synology NAS storage system that is being monitored

Configurable parameters for the test

Parameter

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.

EngineID

This parameter appears only when v3 is selected as the SNMPVersion. Sometimes, the test may not report metrics when AES192 or AES256 is chosen as the Encryption type. To ensure that the test report metrics consistently, administrators need to set this flag to Yes. By default, this parameter is set to No.

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.

Measurements made by the test
Measurement Description Measurement Unit Interpretation

Read throughput

Indicates the rate at which data was read from this LUN.

MB/sec

Comparing the value of these measures across the LUNs will clearly indicate which LUN is the busiest in terms of the rate at which data is read and written - it could also shed light on irregularities in load balancing across the LUNs.

 

Write throughput

Indicates the rate at which data was written to this LUN.

MB/sec

Read IOPS

Indicates the rate at which I/O operations were performed for reading data from this LUN.

Operations/sec

Ideally, the value of this measure should be high. A steady dip in this measure value could indicate a potential reading bottleneck.

Compare the value of this measure across LUNs to identify the LUN that is the busiest in terms of I/O operations that are performed for reading the data from the LUN.

Write IOPS

Indicates the rate at which I/O operations were performed for writing data to this LUN.

Operations/sec

Ideally, the value of this measure should be high. A steady dip in this measure value could indicate a potential writing bottleneck.

Compare the value of this measure across LUNs to identify the LUN that is the busiest in terms of I/O operations that are performed for writing the data to the LUN.

Disk read latency

Indicates the time taken to read the data from this LUN.

Milliseconds

Ideally, this value should be low. A high value could indicate that read operations are slowing down for some reason.

Compare the value of this measure across LUNs to identify the LUN on which slowness is experienced while reading the data from the LUN.

Disk write latency

Indicates the time taken to write the data to this LUN.

Milliseconds

Ideally, this value should be low. A high value could indicate that write operations are slowing down for some reason.

Compare the value of this measure across LUNs to identify the LUN on which slowness is experienced while writing the data to the LUN.

Network transfer data latency

Indicates the time taken to transfer the data from this LUN over the network.

Milliseconds

 

Network receive data latency

Indicates the time taken by this LUN to receive the data over the network.

Milliseconds

 

Average disk latency

Indicates the average time taken by the disk associated with this LUN to perform read and write operations.

Milliseconds

Ideally, this value should be low. A high value could indicate that read and operations are slowing down for some reason.