Monitoring Storage Gateway - AWS Storage Gateway
Understanding Gateway MetricsDimensions for AWS Storage Gateway MetricsMonitoring the Upload BufferMonitoring Cache Storage

Monitoring Storage Gateway

In this section, you can find information about how to monitor a gateway, including monitoring resources associated with the gateway and monitoring the upload buffer and cache storage. You use the AWS Management Console to view metrics for your gateway. For example, you can view the number of bytes used in read and write operations, the time spent in read and write operations, and the time taken to retrieve data from the AWS cloud. With metrics, you can track the health of your gateway and set up alarms to notify you when one or more metrics fall outside a defined threshold.

Topics

AWS Storage Gateway provides Amazon CloudWatch metrics at no additional charge. Storage Gateway metrics are recorded for a period of two weeks. By using these metrics, you can access historical information and get a better perspective on how your gateway and volumes are performing. For detailed information about CloudWatch, see the Amazon CloudWatch User Guide.

Understanding Gateway Metrics

For the discussion in this topic, we define gateway metrics as metrics that are scoped to the gateway—that is, they measure something about the gateway. Because a gateway contains one or more volumes, a gateway-specific metric is representative of all volumes on the gateway. For example, the CloudBytesUploaded metric is the total number of bytes that the gateway sent to the cloud during the reporting period. This metric includes the activity of all the volumes on the gateway.

When working with gateway metric data, you specify the unique identification of the gateway that you are interested in viewing metrics for. To do this, you specify both the GatewayId and the GatewayName values. When you want to work with metric for a gateway, you specify the gateway dimension in the metrics namespace, which distinguishes a gateway-specific metric from a volume-specific metric. For more information, see Using Amazon CloudWatch Metrics.

Topics

    Metric Description Applies To
    CacheHitPercent

    Percent of application reads served from the cache. The sample is taken at the end of the reporting period.

    Unit: Percent

    File, cached-volume, and tape gateways.
    UploadBufferPercentUsed

    Percent use of the gateway's upload buffer. The sample is taken at the end of the reporting period.

    Unit: Percent

    		 Cached-volume and tape gateways.
    UploadBufferUsed

    The total number of bytes being used in the gateway's upload buffer. The sample is taken at the end of the reporting period.

    Unit: Bytes

    Cached-volume and tape gateways.
    CacheUsed

    The total number of bytes being used in the gateway's cache storage. The sample is taken at the end of the reporting period.

    Unit: Bytes

    File, cached-volume, and tape gateways.
    QueuedWrites

    The number of bytes waiting to be written to AWS, sampled at the end of the reporting period for all volumes in the gateway. These bytes are kept in your gateway's working storage.

    Unit: Bytes

    File, cached-volume, stored-volume, and tape gateways.
    ReadBytes

    The total number of bytes read from your on-premises applications in the reporting period for all volumes in the gateway.

    Use this metric with the Sum statistic to measure throughput and with the Samples statistic to measure IOPS.

    Unit: Bytes

    File, cached-volume, and stored-volume gateways.
    ReadTime

    The total number of milliseconds spent to do read operations from your on-premises applications in the reporting period for all volumes in the gateway.

    Use this metric with the Average statistic to measure latency.

    Unit: Milliseconds

    File, cached-volume, and stored-volume gateways.
    TimeSinceLastRecoveryPoint

    The time since the last available recovery point. For more information, see Your Cached Gateway is Unreachable And You Want to Recover Your Data.

    Unit: Seconds

    Cached volumes and stored volumes.
    WorkingStorageFree

    The total amount of unused space in the gateway's working storage. The sample is taken at the end of the reporting period.

    Unit: Bytes

    Stored volumes only.
    WorkingStoragePercentUsed

    Percent use of the gateway's upload buffer. The sample is taken at the end of the reporting period.

    Unit: Percent

    Stored volumes only.
    WorkingStorageUsed

    The total number of bytes being used in the gateway's upload buffer. The sample is taken at the end of the reporting period.

    Unit: Bytes

    Stored volumes only.
    UserCpuPercent

    Percent of CPU time spent on gateway processing, averaged across all cores.

    Unit: Percent

    File gateways only.
    IoWaitPercent

    Percent of time that the gateway is waiting on a response from the local disk.

    Unit: Percent

    File gateways only.
    MemTotalBytes

    Amount of RAM provisioned to the gateway VM, in bytes.

    Unit: Bytes

    File gateways only.
    MemUsedBytes

    Amount of RAM currently in use by the gateway VM, in bytes.

    Unit: Bytes

    File gateways only.
    TotalCacheSize

    The total size of the cache in bytes. The sample is taken at the end of the reporting period.

    Unit: Bytes

    File, cached-volume, and tape gateways.
    WriteBytes

    The total number of bytes written to your on-premises applications in the reporting period for all volumes in the gateway.

    Use this metric with the Sum statistic to measure throughput and with the Samples statistic to measure IOPS.

    Unit: Bytes

    File, cached-volume, and stored-volume gateways.
    WriteTime

    The total number of milliseconds spent to do write operations from your on-premises applications in the reporting period for all volumes in the gateway.

    Use this metric with the Average statistic to measure latency.

    Unit: Milliseconds

    File, cached-volume, and stored-volume gateways.
    TimeSinceLastRecoveryPoint

    The time since the last available recovery point. For more information, see Your Cached Gateway is Unreachable And You Want to Recover Your Data.

    Unit: Seconds

    Cached volumes and stored volumes.
    WorkingStorageFree

    The total amount of unused space in the gateway's working storage. The sample is taken at the end of the reporting period.

    Unit: Bytes

    Stored volumes only.
    WorkingStoragePercentUsed

    Percent use of the gateway's upload buffer. The sample is taken at the end of the reporting period.

    Unit: Percent

    Stored volumes only.
    WorkingStorageUsed

    The total number of bytes being used in the gateway's upload buffer. The sample is taken at the end of the reporting period.

    Unit: Bytes

    Stored volumes only.
    UserCpuPercent

    Percent of CPU time spent on gateway processing, averaged across all cores.

    Unit: Percent

    File, cached-volume, stored-volume, and tape gateways.
    IoWaitPercent

    Percent of time that the gateway is waiting on a response from the local disk.

    Unit: Percent

    File, cached-volume, stored-volume, and tape gateways.
    MemTotalBytes

    Amount of RAM provisioned to the gateway VM, in bytes.

    Unit: Bytes

    File, cached-volume, stored-volume, and tape gateways.
    MemUsedBytes

    Amount of RAM currently in use by the gateway VM, in bytes.

    Unit: Bytes

    File, cached-volume, stored-volume, and tape gateways.
    SmbV1Sessions

    The number of Server Message Block (SMB) version 1 sessions that are active on the gateway.

    Unit: Number

    File gateways only.
    SmbV2Sessions

    The number of SMB version 2 sessions that are active on the gateway.

    Unit: Number

    File gateways only.
    SmbV3Sessions

    The number of SMB version 3 sessions that are active on the gateway.

    Unit: Number

    File gateways only.
    IndexEvictions

    The number of files whose metadata was evicted from the cached index of file metadata to make room for new entries. The gateway maintains this metadata index, which is populated from the AWS Cloud on demand.

    Statistics: SampleCount for number of directories, SUM for total number of files, Average for average number of files per directory.

    Unit: Number

    File gateways only.
    IndexFetches The number of files for which metadata was fetched. The gateway maintains a cached index of file metadata, which is populated from the AWS Cloud on demand.

    Statistics: SampleCount for number of directories, SUM for total number of files, Average for average number of files per directory.

    Unit: Number

    File gateways only.
    AvailabilityNotifications

    Number of availability-related health notifications generated by the gateway.

    Use this metric with the Sum statistic to observe whether the gateway is experiencing any availability-related events. For details about the events, check your configured CloudWatch log group.

    Unit: Number

    All gateways.

    Dimensions for AWS Storage Gateway Metrics

    The Amazon CloudWatch namespace for the AWS Storage Gateway service is AWS/StorageGateway. Data is available automatically in 5-minute periods at no charge.

    Dimension

    Description
    GatewayId, GatewayName

    These dimensions filter the data that you request to gateway-specific metrics. You can identify a gateway to work by the value for GatewayId or GatewayName. If the name of your gateway was different for the time range that you are interested in viewing metrics, use the GatewayId.

    Throughput and latency data of a gateway is based on all the volumes for the gateway. For information about working with gateway metrics, see Measuring Performance Between Your Gateway and AWS.

    VolumeId

    This dimension filters the data you request to volume-specific metrics. Identify a storage volume to work with by its VolumeId value. For information about working with volume metrics, see Measuring Performance Between Your Application and Gateway.

    Monitoring the Upload Buffer

    You can find information following about how to monitor a gateway's upload buffer and how to create an alarm so that you get a notification when the buffer exceeds a specified threshold. By using this approach, you can add buffer storage to a gateway before it fills completely and your storage application stops backing up to AWS.

    You monitor the upload buffer in the same way in both the cached-volume and tape gateway architectures. For more information, see How AWS Storage Gateway Works (Architecture).

    Note

    The WorkingStoragePercentUsed, WorkingStorageUsed, and WorkingStorageFree metrics represent the upload buffer for stored volumes only before the release of the cached-volume feature in Storage Gateway. Now, use the equivalent upload buffer metrics UploadBufferPercentUsed, UploadBufferUsed, and UploadBufferFree. These metrics apply to both gateway architectures.

    Item of Interest How to Measure
    Upload buffer usage

    Use the UploadBufferPercentUsed, UploadBufferUsed, and UploadBufferFree metrics with the Average statistic. For example, use the UploadBufferUsed with the Average statistic to analyze the storage usage over a time period.

    To measure the percent of the upload buffer that is used

    1. Open the CloudWatch console at https://console.aws.amazon.com/cloudwatch/.

    2. Choose the StorageGateway: Gateway Metrics dimension, and find the gateway that you want to work with.

    3. Choose the UploadBufferPercentUsed metric.

    4. For Time Range, choose a value.

    5. Choose the Average statistic.

    6. For Period, choose a value of 5 minutes to match the default reporting time.

    The resulting time-ordered set of data points contains the percent used of the upload buffer.

    Using the following procedure, you can create an alarm using the CloudWatch console. To learn more about alarms and thresholds, see Creating CloudWatch Alarms in the Amazon CloudWatch User Guide.

    To set an upper threshold alarm for a gateway's upload buffer

    1. Open the CloudWatch console at https://console.aws.amazon.com/cloudwatch/.

    2. Choose Create Alarm to start the Create Alarm wizard.

    3. Specify a metric for your alarm:

      1. On the Select Metric page of the Create Alarm wizard, choose the AWS/StorageGateway:GatewayId,GatewayName dimension, and then find the gateway that you want to work with.

      2. Choose the UploadBufferPercentUsed metric. Use the Average statistic and a period of 5 minutes.

      3. Choose Continue.

    4. Define the alarm name, description, and threshold:

      1. On the Define Alarm page of the Create Alarm wizard, identify your alarm by giving it a name and description in the Name and Description boxes.

      2. Define the alarm threshold.

      3. Choose Continue.

    5. Configure an email action for the alarm:

      1. On the Configure Actions page of the Create Alarm wizard, choose Alarm for Alarm State.

      2. Choose Choose or create email topic for Topic.

        To create an email topic means that you set up an Amazon SNS topic. For more information about Amazon SNS, see Set Up Amazon SNS in Amazon CloudWatch User Guide.

      3. For Topic, enter a descriptive name for the topic.

      4. Choose Add Action.

      5. Choose Continue.

    6. Review the alarm settings, and then create the alarm:

      1. On the Review page of the Create Alarm wizard, review the alarm definition, metric, and associated actions to take (for example, sending an email notification).

      2. After reviewing the alarm summary, choose Save Alarm.

    7. Confirm your subscription to the alarm topic:

      1. Open the Amazon SNS email that was sent to the email address that you specified when creating the topic.

        The following image shows a typical email notification.

      2. Confirm your subscription by clicking the link in the email.

        A subscription confirmation appears.

    Monitoring Cache Storage

    You can find information following about how to monitor a gateway's cache storage and how to create an alarm so that you get a notification when parameters of the cache pass specified thresholds. Using this alarm, you know when to add cache storage to a gateway.

    You only monitor cache storage in the cached volumes architecture. For more information, see How AWS Storage Gateway Works (Architecture).

    Item of Interest How to Measure
    Total usage of cache

    Use the CachePercentUsed and TotalCacheSize metrics with the Average statistic. For example, use the CachePercentUsed with the Average statistic to analyze the cache usage over a period of time.

    The TotalCacheSize metric changes only when you add cache to the gateway.

    Percent of read requests that are served from the cache

    Use the CacheHitPercent metric with the Average statistic.

    Typically, you want CacheHitPercent to remain high.

    Percent of the cache that is dirty—that is, it contains content that has not been uploaded to AWS

    Use the CachePercentDirty metrics with the Average statistic.

    Typically, you want CachePercentDirty to remain low.

    To measure the percent of a cache that is dirty for a gateway and all its volumes

    1. Open the CloudWatch console at https://console.aws.amazon.com/cloudwatch/.

    2. Choose the StorageGateway: Gateway Metrics dimension, and find the gateway that you want to work with.

    3. Choose the CachePercentDirty metric.

    4. For Time Range, choose a value.

    5. Choose the Average statistic.

    6. For Period, choose a value of 5 minutes to match the default reporting time.

    The resulting time-ordered set of data points contains the percentage of the cache that is dirty over the 5 minutes.

    To measure the percent of the cache that is dirty for a volume

    1. Open the CloudWatch console at https://console.aws.amazon.com/cloudwatch/.

    2. Choose the StorageGateway: Volume Metrics dimension, and find the volume that you want to work with.

    3. Choose the CachePercentDirty metric.

    4. For Time Range, choose a value.

    5. Choose the Average statistic.

    6. For Period, choose a value of 5 minutes to match the default reporting time.

    The resulting time-ordered set of data points contains the percentage of the cache that is dirty over the 5 minutes.