eG Monitoring
 

Measures reported by AlibabaStorageTest

Cloud disks are block-level Elastic Block Storage (EBS) products provided by Alibaba Cloud for ECS and provide low latency, high performance, high durability, and high reliability. Cloud disks use a distributed triplicate mechanism to ensure 99.9999999% (nine 9's) data durability for ECS instances. If service disruptions occur within a zone (for example, due to hardware failures), data within the zone is copied to an available disk in another zone to help ensure data availability.

Cloud disks are classified into the following categories based on their performance:

  • Enhanced SSDs (ESSDs): ESSDs are based on the next-generation distributed block storage architecture and the 25 Gigabit Ethernet (25 GE) and remote direct memory access (RDMA) technologies. Each ESSD has low latency and can deliver up to one million input/output operations per second (IOPS).

  • Standard SSDs: Standard SSDs are high-performance disks that provide consistent high random IOPS and high data reliability.

  • Ultra disks: Ultra disks are cost-effective and provide medium random IOPS and high data reliability.

  • Basic disks: Basic disks are the previous generation of disks and are unavailable for purchase.

Cloud disks are classified into system disks and data disks based on their purpose.

  • System disks contain operating systems and can be created only along with instances. The lifecycle of a system disk is the same as that of the instance to which the system disk is attached.

  • Data disks are used to store application data and can be created separately or along with instances.

If a system/data disk is suddenly detached/deleted, all instances attached to such disks will be adversely impacted. For instance, without access to the OS files stored in the system disk, the instance may not even boot up. Likewise, the loss of application data in the data disk, may degrade application performance and may also affect user productivity. This is why, before initiating a disk detach/delete operation, administrators must first determine which instances are attached to the disk, and then analyze how the deletion/detachment of the disk will impact the instances

Using the AlibabaStorageTest test, you can closely monitor the status of each cloud disk and learn what features/properties are enabled for every disk. In the process, detaching disks can be rapidly identified. The test also reports the count and details of instances attached to each disk, thus enabling administrators quickly figure out which instances will be impacted when a disk is deleted or is in the ‘Deleting’ state.

Outputs of the test : One set of results for each cloud disk.

The measures made by this test are as follows:

Measurement Description Measurement Unit Interpretation
Disk_state Indicates the current status of this disk.   The values that this measure reports and their corresponding numeric values are listed below:

Measure Value Description Numeric Value
Creating After a disk is created by calling the RunInstances, CreateInstance, or CreateDisk operation, the disk enters the Creating state. 1
Available After a pay-as-you-go disk is created by calling the CreateDisk operation or a pay-as-you-go data disk is detached by calling the DetachDisk operation, the disk enters the Unattached or Available state. 2
In-use The disk is in use. 3
Attaching If a pay-as-you-go data disk is attached by using AttachDisk operation, the disk enters the Attaching state. 4
Detaching After a pay-as-you-go data disk is detached by calling the DetachDisk operation, the disk enters the Detaching state 5
Reiniting After you reinitialize a system or data disk by calling the ReInitDisk operation, the disk enters the Initializing state. 6

Note:

This measure reports the Measure Values listed in the table above to indicate the current state of a cloud disk. In the graph of this measure however, the same is indicated using the numeric equivalents only.

Use the detailed diagnosis of this measure to know more about the disk. Such details include the disk type, when the disk was created, the image that stores a copy of the data in the disk, and the zone to which the disk belongs.
Deleted_instance Indicates whether this disk is configured to be released when the associated instance is released. Number The values that this measure reports, their descriptions, and their corresponding numeric values are listed below:

Measure Value Description Numeric Value
True The disk is released when its associated instance is released. 1
False The disk is not released but is retained as a payas-you-go data disk when its associated instance is released. 0

Note:

This measure reports the Measure Values listed in the table above to indicate whether/not the disk will be released with its instance. In the graph of this measure however, the same is indicated using the numeric equivalents only.
Deleted_snapshot Indicates whether the automatic snapshots of the disk are deleted when the disk is released.   Automatic snapshot policies allow ECS to create normal snapshots and back up data for a disk on a regular basis. These policies can be applied to both system disks and data disks. Automatic snapshot policies improve data security and tolerance against operation faults.

You can enable the Delete Automatic Snapshots While Releasing Disk feature to delete automatic snapshots of a disk when the disk is released and reduce the amount of disk space occupied by snapshots. Using the value reported by this measure, you can figure out if this feature has been enabled for this disk or not.

The values that this measure reports and their corresponding numeric values are listed below:

Measure Value Numeric Value
True 1
False 0

Note:

This measure reports the Measure Values listed in the table above to indicate whether/not auto snapshots will be deleted when the disk is released. In the graph of this measure however, the same is indicated using the numeric equivalents only.
Enabled_snapshot Indicates whether/not the automatic snapshot policy is enabled for this disk.   Automatic snapshot policies allow ECS to create normal snapshots and back up data for a disk on a regular basis. Such policies improve data security and tolerance against operation faults.

Using the value reported by this measure, you can figure out if the Automatic Snapshot Policy feature is enabled for this disk or not.

The values that this measure reports and their corresponding numeric values are listed below:

Measure Value Numeric Value
True 1
False 0

Note:

This measure reports the Measure Values listed in the table above to indicate whether/not Automatic Snapshot Policy feature is enabled for the disk. In the graph of this measure however, the same is indicated using the numeric equivalents only.
Snapshot_policy Indicates whether an automatic snapshot policy is applied to the disk.   Automatic snapshot policies allow ECS to create normal snapshots and back up data for a disk on a regular basis. Such policies improve data security and tolerance against operation faults.

Once the Automatic Snapshot Policy feature is enabled for a disk, you need to create a policy and then apply it to the disk before you can use that policy.

Using the value reported by this measure, you can figure out if any such policy has applied to this disk.

The values that this measure reports and their corresponding numeric values are listed below:

Measure Value Numeric Value
True 1
False 0

Note:

This measure reports the Measure Values listed in the table above to indicate whether/not any automatic snapshot policy has been applied to the disk. In the graph of this measure however, the same is indicated using the numeric equivalents only.
Disk_encrypt Indicates whether/not this disk is encrypted.   The values that this measure reports and their corresponding numeric values are listed below:

Measure Value Numeric Value
True 1
False 0

Note:

This measure reports the Measure Values listed in the table above to indicate whether/not the disk is encrypted. In the graph of this measure however, the same is indicated using the numeric equivalents only.
Disk_size Indicates the size of this disk. GB Observe the variations to this measure over time to capture abnormal growth (if any) in disk size.
Attached_instance Indicates the number of ECS instances that are attached to this disk. Number Use the detailed diagnosis of this measure to identify the instances that are attached to this disk.