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ETERNUS SF Storage Cruiser 14.0 User's Guide

7.6.1 Delay in LogicalVolume response

Report Detail:
The response time delay of LogicalVolume YYYY that is defined to RAIDGroup XXXX was detected.
The monitoring condition of the other object that it is related is as follows.
CM Monitoring Condition :   <- (1)
[CM0x00] Alarm
[CM0x01] Normal
[CM0x10] Normal
[CM0x11] Normal

Monitoring condition of RAIDGroup XXXX : Alarm   <- (2)

The block size of I/O at the time of the response time delay detection is 8K bytes.   <- (3)

Relevant Graph :
Please refer to the response time graph of LogicalVolume YYYY.

Action :
1. There is the possibility of RAIDGroup overload condition. Please confirm the RAIDGroup overload alarm and 
refer the measure guide.
2. There is the possibility of CM overload condition.Please confirm the CM overload alarm and refer the measure guide.
If the device has ROE, there is the possibility of ROE overload condition. Please refer to ROE busy rate.
If the ROE detected a high load state, refer to the busy rate of each CM, and distribute I/O to RAIDGroups
under control of a CM with a low load.
3. It is posible that time is required to I/O processing because the block size is big.
Please review the threshold value.
Description of (1)

Indicates the state of each CM during the same time zone as the LogicalVolume response delay is detected. However, the state of each ROE is not indicated.

Alarm

An alarm log indicating a CM load error is generated during the same time zone. If the CM in charge of the LogicalVolume in which a response delay was detected is in the high load state, a response delay due to a CM bottleneck is assumed. Refer to the guidelines for corrective measures for alarms for the relevant CM.

Monitoring

The CM is monitoring for alarm detection because the threshold has been exceeded several times although no events have been detected as an alarm.

Normal

  • When the CM busy rate is defined as a threshold monitoring target
    No CM bottleneck has occurred during the same time zone.Check the RAIDGroup defining the LogicalVolume for alarms.

  • When the CM busy rate is not defined as a threshold monitoring target
    The CM busy rate is not monitored.
    ("Not detected" is displayed irrespective of the CM busy rate.)

Description of (2)

Indicates the state of the RAIDGroup in which the relevant LogicalVolume is defined during the same time zone as the LogicalVolume response delay is detected.

High load state detected

An alarm log indicating a RAIDGroup load error is generated during the same time zone. A response delay due to bottlenecks of disks configuring a RAID is assumed. Refer to the guidelines for RAIDGroup corrective measures for alarms for the relevant RAIDGroup.

Monitoring

The CM is monitoring for alarm detection because the threshold has been exceeded several times although no events have been detected as an alarm.

Not detected

  • When the RAIDGroup busy rate is defined as a threshold monitoring target
    There is no bottleneck of disks comprising the RAID in the same time zone.

  • When the RAIDGroup busy rate is not defined as a threshold monitoring target
    The RAIDGroup busy rate is not monitored.
    ("Not detected" is displayed irrespective of the RAIDGroup busy rate.)

Descrition of (3)

Indicates the I/O block size at the time of detection of a LogicalVolume delay response.
If the CM and ROE in charge of the relevant LogicalVolume or the ROE for assigned CM or the defined RAIDGroup is not in the high load state, an alarm is not attributable to CM and disk bottlenecks but may be attributable to an unreasonably large I/O block size for the threshold.
For instance, when a response delay is detected while the threshold of the LogicalVolume response is set to 30 ms, no CM and disk bottlenecks have occurred, but the I/O block size may be 512K bytes. In this case, the most highly probable cause of the response delay is a large I/O block size. Generally, the larger the I/O block size, the larger the response delay. When the standard response is set to 30 ms, an I/O block size of 512K bytes or more is a rough indication for a response delay due to the I/O block size.
Take measures such as reviewing the threshold of the LogicalVolume response or reducing the I/O block size in the application.