Oracle FS1-2 Flash Storage System
 

PLA-Support>Sun Systems>DISK>Flash Storage>SN-EStor: FSx
 

In this Document

Symptoms

Cause

Solution

References

Created from <SR 3-11170801271>

Applies to:

Symptoms

This document only applies for FS1-2 that are on release 6.1.x

In software release 6.2.1 and higher there is a software code change that will prevent Auto Tiered LUNs going into Conservative mode (Write-Through mode) when the Infill reserve has reached the limit to avoid data loss. The change restricts Auto-tier allocations to twice the Infill Reserve to suspend allocation in the filling Class and trigger Auto-tier compaction before the reserve limit is reached. If mixed standard and Auto-tiered LUNs are configured on the same Storage Domain, it is advisable to limit the amount of storage allocated to Auto-tier to less than 100%.

The fix for this issue is tracked under Bug 21607338 and it's mentioned in the 6.2.3 README. So please make sure customer's upgrade their FS1-2 to latest GA release to avoid this issue that is described in this document.

Higher latency times are noticed with LUNs when free space is low for a Storage Class within a Storage Domain.

In the GUI -> "System" tab -> "Event Log", there will be Warning events indicating Storage Pool Nearing Allocation Limit.  Viewing the details of the event will report which Storage Class within the Storage Domain is low on free space.

From an FS1-2 logset this can be seen in the *.events.xml file, below is a sample of the event:

<GetSystemEventResponse>
  <SystemEventInformation>
    <EventType>STORAGE_POOL_NEARING_ALLOCATION_LIMIT</EventType>
    <Severity>WARNING</Severity>
    <Category>SYSTEM</Category>
    <Time>2015-08-09T02:34:34.850</Time>
    <ComponentIdentity>
      <Guid>414B303032373131A214000000000000</Guid>
    </ComponentIdentity>
    <ComponentName>/Storage Domain 1</ComponentName>
    <EventParameterList>
      <ParameterName>EventParameters.storageClass</ParameterName>
      <ParameterValue>STORAGE_CLASS_PERF_HDD</ParameterValue>
    </EventParameterList>
    <EventParameterList>
      <ParameterName>EventParameters.usedCapacity</ParameterName>
      <ParameterValue>21039541125120</ParameterValue>
    </EventParameterList>
    <EventParameterList>
      <ParameterName>EventParameters.totalCapacity</ParameterName>
      <ParameterValue>21484126863360</ParameterValue>
    </EventParameterList>
    <EventGuid>0010E062ECB40000003AC0F1CA2E000D</EventGuid>
  </SystemEventInformation>
</GetSystemEventResponse>

To check how much free space a storage class has view *.chsh.xml file look for <StorageDetailsInformation> xml tag, then scroll down until you see xml tag <StorageDomainDetails> in this section look for the Storage Domain of interest and view the capacity details for the storage class:

<StorageDomainDetails>
    <StorageDomainIdentity>
      <Id>414B303032373131A214000000000000</Id>
      <Fqn>/Storage Domain 1</Fqn>
    </StorageDomainIdentity>
    <StorageClassDetails>
      <StorageClass>STORAGE_CLASS_PERF_HDD</StorageClass>
      <CapacitySummary>
        <PhysicalFreeCapacity>49</PhysicalFreeCapacity>
        <PhysicalFreeCapacityInBytes>53508833280</PhysicalFreeCapacityInBytes>
        <PhysicalUsedCapacity>15280</PhysicalUsedCapacity>
        <PhysicalUsedCapacityInBytes>16407433004494</PhysicalUsedCapacityInBytes>
        <PhysicalTotalCapacity>20008</PhysicalTotalCapacity>
        <PhysicalTotalCapacityInBytes>21484126863360</PhysicalTotalCapacityInBytes>
        <PhysicalAllocatedCapacity>19958</PhysicalAllocatedCapacity>
        <PhysicalAllocatedCapacityInBytes>21430618030080</PhysicalAllocatedCapacityInBytes>
        <PhysicalUnavailableCapacity>0</PhysicalUnavailableCapacity>
        <PhysicalUnavailableCapacityInBytes>0</PhysicalUnavailableCapacityInBytes>
        <PhysicalMaximumCommittedCapacity>82377</PhysicalMaximumCommittedCapacity>
        <PhysicalMaximumCommittedCapacityInBytes>88452452843520</PhysicalMaximumCommittedCapacityInBytes>
      </CapacitySummary>
    </StorageClassDetails>

In this example Storage Domain 1 Storage Class Perf HDD has 49GB of free space.

You can also execute FSInfo.pl -u command to view this information.

Cause

When there is not a sufficient amount of free space in the Storage Class LUNs will be enabled in Write-Through mode which will cause LUNs to perform more slowly.

For Perf and Capacity HDD Storage Classes, please ensure there is more than 50GB of free storage space for each Storage Class. If free space in the Perf and Capacity HDD Storage Classes is 50GB or less then LUNs will be enabled in Write-Through mode causing higher latency times.

For Perf and Capacity SSD Storage Classes, please ensure there is more than 25GB of free storage space for each Storage Class. If free space in the Perf and Capacity SSD Storage Classes is 25GB or less then LUNs will be enabled in Write-Through mode causing higher latency times.

Solution

The solution is to free up space for the Storage Class that is low on free space.  There are few options to consider when freeing up space on Storage Class:

• Move LUNs from the Storage Class low on space to another Storage Class that has enough free space
• Change the percentage of allocation on each storage class for tiered volumes to reclaim space. This will launch a compaction task.
• Consider Deleting data or LUNs on the Storage Class that is low on space.
• Add additional storage.

If moving LUNs from a Storage Class that is low on space to another Storage Class, or Deleting data or LUNs on the Storage Class that is low on space may not free space immediately. If space is not reclaimed sometime after freeing additional space in the Storage Class consider initiating a Storage Domain Compaction, for more information see <Document 2015849.1> FS System: Deleting Auto-Tier LUNs May Not Increase Free Space for a Storage Domain

References

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