XIO Snapshots Test

Snapshots are instantaneous copy images of volume data with the state of the data captured exactly as it appeared at the specific point in time that the snapshot was created, enabling users to save the volume data state and then access the specific volume data whenever needed, including after the source volume has changed.

Creating snapshots, which can be done at any time, does not affect system performance, and a snapshot can be taken either directly from a source volume or from other snapshots within a source volume’s group (Volume Snapshot Group).

The original copy of the data remains available without interruption, while the snapshot can be used to perform other functions on the data. Changes made to the snapshot’s source do not change or impact on the snapshot data.

XtremIO snapshots are read-write. Users can choose to mount the snapshot in read-only (host side or from the host) in order to maintain its immutability.

XtremIO's snapshot technology is implemented by leveraging the content-aware capabilities of the system (Inline Data Reduction), optimized for SSD media, with a unique metadata tree structure that directs I/O to the right timestamp of the data. This allows efficient snapshotting that can sustain high performance, while maximizing the media endurance, both in terms of the ability to create multiple snapshots and the amount of I/O that a snapshot can support. To analyze the performance of snapshots, administrators can use the XIO Snapshots test.

This test auto-discovers the snapshots of the target storage array and helps administrators to figure out the snapshot that is busy processing I/O requests, detect irregularities in the distribution of I/O load across the snapshots. In addition, using this test, administrators can analyze the space utilization of each snapshot and thus figure out remedial measures to keep a check on the irregularities detected.

Target of the test : An EMC XtremIO Storage array

Agent deploying the test : A remote agent

Outputs of the test : One set of results for each snapshot available in the target EMC XtremIO being monitored.

Configurable parameters for the test

Parameter	Description
Test Period	How often should the test be executed.
Host	The IP address of the storage device for which this test is to be configured.
Port	The port number at which the storage array listens. The default is NULL.
XtremIO User and XtremIO Password	Provide the credentials of a user who has read only privileges to access the XtremIO storage array in the XtremIO User and XtremIO Password text boxes.
Confirm Password	Confirm the password by retyping it here.
XMS IP	This parameter is applicable only for EMC XtremIO 4.x. By default, None will be chosen from this list. If the target EMC XtremIO storage array is within a XMS Management Server that is auto-discovered, then the IP or host name of that XMS Management Server will be displayed in this list. Select that particular XMS IP to configure this test. If you wish to monitor an EMC XtremIO Storage Array that is either not an integral part of the auto-discovered XMS Management Server or a brand new EMC XtremIO Storage Array, choose the Other option. This will enable you to add a new XMS Managament Server. To know how to add a new XMS Management Server, refer to Adding a new XMS.
SSL	The eG agent collects performance metrics by invoking Restful APIs on the target Storage array. Typically, the Restful APIs can be invoked through the HTTP or the HTTPS mode. By default, the eG agent invokes the Restful APIs using the HTTPS mode. This is why, the SSL flag is set to Yes by default. If the target storage array is not SSL-enabled, then the Restful APIs can be accessed through the HTTP mode only. In this case, set the SSL flag to No.

Measurements made by the test

Measurement	Description	Measurement Unit	Interpretation
Bandwidth	Indicates the amount of data utilized for performing I/O operations per second on this snapshot.	MB/Sec
Read bandwidth	Indicates the amount of data utilized for performing read I/O operations per second on this snapshot.	MB/Sec
Write bandwidth	Indicates the amount of data utilized for performing write I/O operations per second on this snapshot.	MB/Sec
IOPS	Indicates the rate at which I/O operations were performed on this snapshot during the last measurement period.	IOPS	Compare the value of this measure across the snapshots to know which snapshot handles the maximum number of I/O operations
Read IOPS	Indicates the rate at which read operations were performed on this snapshot.	IOPS
Write IOPS	Indicates the rate at which write operations were performed on this snapshot.	IOPS
Reads	Indicates the number of reads performed on this snapshot per second during the last measurement period.	Reads/sec	Compare the value of this measure across the snapshots to know which snapshot handles the maximum number of read requests.
Writes	Indicates the number of writes performed on this snapshot per second during the last measurement period.	Writes/sec
Data reads	Indicates the rate at which data was read from this snapshot during the last measurement period.	MB/Sec
Data written	Indicates the rate at which data was written to this snapshot during the last measurement period.	MB/Sec
Average read size	Indicates the amount of data read from this snapshot per I/O operation during the last measurement period.	MB/Op	Compare the values of these measures across the snapshots to identify the snapshot that is the slowest in terms of servicing read and write requests (respectively).
Average write size	Indicates the amount of data written to this snapshot per I/O operation during the last measurement period.	MB/Op
Read latency	Indicates the time taken to perform read operations on this snapshot.	msecs
Write latency	Indicates the time taken to perform write operations on this snapshot.	msecs
Average latency	Indicates the average time taken to perform I/O operations on this snapshot.	msecs
Number of destination snaps	Indicates the number of volumes that were generated from this snapshot.	Number	By default, volumes are snapshotted at equal intervals and these snapshots are distributed to various clients whereas the original volume is maintained as the source copy. If the value of this measure is high, then administrators may be required to correlate this value with that of the Bandwidth measure. The higher the value of this measure, the greater is the bandwidth utilized. Therefore, for the bandwidth to be maintained in an optimal range, the value of this measure should be maintained within the permissible limits. If too many snapshots are created within a short period of time, then the optimization of the storage array may fail leading to severe processing bottlenecks.
Free snap size	Indicates the amount of space allocated for this snapshot.	GB
Used snap size	Indicates the amount of space utilized by this snapshot.	GB
Free snap size Percent	Indicates the percentage of space allocated for this snapshot.	Percent
Used snap size Percent	Indicates the percentage of space utilized by this snapshot.	Percent	A value close to 100 indicates that the snapshot is running out of space.