NetApp iSCSI Protocol Test
The iSCSI protocol is a licensed service on the storage system that enables you to transfer block data to hosts using the SCSI protocol over TCP/IP. The iSCSI protocol standard is defined by RFC 3720. In an iSCSI network, storage systems are targets that have storage target devices, which are referred to as LUNs (logical units). A host with an iSCSI host bus adapter (HBA), or running iSCSI initiator software, uses the iSCSI protocol to access LUNs on a storage system. The iSCSI protocol is implemented over the storage system’s standard gigabit Ethernet interfaces using a software driver. The connection between the initiator and target uses a standard TCP/IP network. No special network configuration is needed to support iSCSI traffic. The network can be a dedicated TCP/IP network, or it can be your regular public network. The storage system listens for iSCSI connections on TCP port 3260.
This test monitors the active and attempted iSCSI sessions on the storage system, and promptly captures the processing ability, login failures, failed tasks, and errors encountered by these sessions.
Target of the test : A NetApp Unified Storage
Agent deploying the test : An external/remote agent
Outputs of the test : One set of results for the NetApp storage system being monitored.
| Parameters | Description |
|---|---|
|
Test Period |
How often should the test be executed. |
|
Host |
The host for which the test is to be configured. |
|
Port |
Specify the port at which the specified host listens in the Port text box. By default, this is NULL. |
|
User |
Here, specify the name of the user who possesses the following privileges: login-http-admin,api-aggr-check-spare-low,api-aggr-list-info,api-aggr-mediascrub-list-info,api-aggr-scrub-list-info,api-cifs-status,api-clone-list-status,api-disk-list-info,api-fcp-adapter-list-info,api-fcp-adapter-stats-list-info,api-fcp-service-status,api-file-get-file-info,api-file-read-file,api-iscsi-connection-list-info,api-iscsi-initiator-list-info,api-iscsi-service-status,api-iscsi-session-list-info,api-iscsi-stats-list-info,api-lun-config-check-alua-conflicts-info,api-lun-config-check-cfmode-info,api-lun-config-check-info,api-lun-config-check-single-image-info,api-lun-list-info,api-nfs-status,api-perf-object-get-instances-iter*,api-perf-object-instance-list-info,api-quota-report-iter*,api-snapshot-list-info,api-vfiler-list-info,api-volume-list-info-iter*. If such a user does not pre-exist, then, you can create a special user for this purpose using the steps detailed in Creating a New User with the Privileges Required for Monitoring the NetApp Unified Storage. |
|
Password |
Specify the password that corresponds to the above-mentioned User. |
|
Confirm Password |
Confirm the Password by retyping it here. |
|
Authentication Mechanism |
In order to collect metrics from the NetApp Unified Storage system, the eG agent connects to the ONTAP management APIs over HTTP or HTTPS. By default, this connection is authenticated using the LOGIN_PASSWORD authentication mechanism. This is why, LOGIN_PASSWORD is displayed as the default authentication mechanism. |
|
Use SSL |
Set the Use SSL flag to Yes, if SSL (Secured Socket Layer) is to be used to connect to the NetApp Unified Storage System, and No if it is not. |
|
API Port |
By default, in most environments, NetApp Unified Storage system listens on port 80 (if not SSL-enabled) or on port 443 (if SSL-enabled) only. This implies that while monitoring the NetApp Unified Storage system, the eG agent, by default, connects to port 80 or 443, depending upon the SSL-enabled status of the NetApp Unified Storage system - i.e., if the NetApp Unified Storage system is not SSL-enabled (i.e., if the Use SSL flag above is set to No), then the eG agent connects to the NetApp Unified Storage system using port 80 by default, and if the NetApp Unified Storage system is SSL-enabled (i.e., if the Use SSL flag is set to Yes), then the agent-NetApp Unified Storage system communication occurs via port 443 by default. Accordingly, the API Port parameter is set to default by default. In some environments however, the default ports 80 or 443 might not apply. In such a case, against the API Port parameter, you can specify the exact port at which the NetApp Unified Storage system in your environment listens, so that the eG agent communicates with that port for collecting metrics from the NetApp Unified Storage system. |
|
vFilerName |
A vFiler is a virtual storage system you create using MultiStore, which enables you to partition the storage and network resources of a single storage system so that it appears as multiple storage systems on the network. If the NetApp Unified Storage system is partitioned to accommodate a set of vFilers, specify the name of the vFiler that you wish to monitor in the vFilerName text box. In some environments, the NetApp Unified Storage system may not be partitioned at all. In such a case, the NetApp Unified Storage system is monitored as a single vFiler and hence the default value of none is displayed in this text box. |
|
Timeout |
Specify the duration (in seconds) beyond which the test will timeout if no response is received from the device. The default is 120 seconds. |
| Measurement | Description | Measurement Unit | Interpretation |
|---|---|---|---|
|
Command Descriptor Blocks CDB processed |
Indicates the total number of Command Descriptor Blocks that were processed by the inititator during the last measurement unit. |
Number |
The SCSI Command Descriptor Block (CDB) is a block of information that describes the command. Commands are sent from SCSI Initiators, which are contained in host computers, to SCSI Targets, which are controllers of some type of storage device (hard disk, tape drive, etc.). Almost every CDB contains 3 parts:
For some commands, these fields are implied or not required. The “What” field is called the Operation Code (or OpCode) and tells the target what the command is supposed to do. A couple of examples would be READ or WRITE. The READ command moves data from the storage device to the host system, while the WRITE command moves data to the storage device for later access. The “Where” field tells the target where to begin the operation and is expressed as a Logical Block Address, or LBA. This address ranges from zero (0) to the maximum address of the device. Some commands, such as INQUIRY, do not require this field. The “How Much” field tells the target how many blocks (or bytes) or data to move. The block size of most storage devices is 512 bytes, but in certain storage devices, the block size can be different. This field is expressed as either Transfer Length (in blocks), Allocation Length (bytes moving to the host), or Parameter List Length (bytes moving to the device). Which name is used depends on the command itself. CDBs come in various sizes, typically 6, 10, 12, or 16 bytes total. Below is a figure of a 10-byte READ command to be sent to a hard drive. This command, if successful, will move one block (512 bytes) of data to the host computer system, from logical block address 100h (hex). All other bits or fields that are not labeled are set to zero. This measure is a good indicator for analyzing the traffic/load in this storage system. |
|
Successfully processed CDBs |
Indicates the number of Command Descriptor Blocks that were successfully executed by the initiator during the last measurement period. |
Number |
A high value is desired for this measure. A low value indicates that there were too many unsuccessful CDB executions, which may have caused a processing bottleneck. |
|
CDBs with errors |
Indicates the number of Command Descriptor Blocks that were processed by the initiators with errors during the last measurement period. |
Number |
Ideally, the value of this measure should be 0. A high value indicates that there were too many errors that occurred while processing the CDBs which may affect the performance of the storage system. Some of the common errors that occur while the CDBs are processed include the medium/hardware errors, providing illegal parameters for the CDB, accessing unauthorized data, volume overflow etc. |
|
Total errors |
Indicates the total number of iSCSI errors that occurred during the last measurement period. |
Number |
Ideally, the value of this measure should be 0. Some of the common iSCSI errors that occur are digest errors, login/logout errors, PDU errors etc. |
|
Failed logins |
Indicates the number of failed login attempts made by the initiator while creating new iSCSI sessions during the last measurement period. |
Number |
Ideally, the value of this measure should be 0. |
|
Failed logouts |
Indicates the number of failed logouts while attempting to gracefully end the iSCSI sessions during the last measurement period. |
Number |
Ideally, the value of this measure should be 0. |
|
Failed tasks |
Indicates the number of iSCSI tasks that failed during the last measurement period. |
Number |
|
|
Protocol errors |
Indicates the number of protocol errors that occurred during the last measurement period. |
Number |
Ideally, the value of this measure should be 0. Protocol errors mainly occur due to the violation of protocol rules. The protocol errors occur in scenarios like violation of iSCSI PDU exchange sequences, duplication of protocol steps, invalid format/entries in protocol messages etc. |
|
Login requests |
Indicates the number of login requests made during the last measurement period. |
Number |
This measure is an actual indicator of the users who are attempting to login to the storage system. Compare this value with the Failed logins measure to find out how well the user requests are processed in this storage system. |
|
Logout requests |
Indicates the number of logout requests made during the last measurement period. |
Number |
This measure is an actual indicator of the users who are attempting to logout of the storage system. Compare this value with the Failed logouts measure to find out how well the user requests are processed in this storage system. |
|
Protocol Data Units rejected |
Indicates the number of Protocol Data Units that were rejected by the initiator during the last measurement period. |
Number |
In a layered system such as iSCSI, a unit of data which is specified in a protocol of a given layer and which consists of protocol-control information and possibly user data of that layer is termed as a Protocol Data Unit. Ideally, the value of this measure should be 0. The Protocol Data Units are rejected due to iSCSI error conditions such as protocol errors, unsupported option etc., which may lead to connection/data loss, performance/processing bottleneck on the storage system etc. |
