For the last few days I was having an issue with my Storage Spaces setup. I have a Two-way Mirror Storage Space comprising of 2 identical SATA-attached HDD drives.
However the Storage Spaces in the Control Panel is showing a Warning without giving any explanation of what is actually wrong (no tooltip or anything). In addition, it shows different values for the used capacity! How can that be in a mirrored, identically sized disks?
Running a few diagnostic commands in PowerShell does not provide much info either:
They basically duplicate the what the Control Panel was displaying. However what struck me was that it showed storage efficiency at 73.98%! This should be exactly 50% for my setup. Does it imply then that a substantial part of the data is out of sync then? If so, how can I resync it, making sure it "knows" which data should be used?
- I have write caching disabled for both drives, so in all cases writes should be immediately reflected on the disks.
- I did use a Hex Editor with raw disk viewing support to check if indeed it mirrors the data. I tried to find very recent files that I have created in the NTFS MFT using Hex Editor, and was able to do so, with the file records for the new files existing at identical sectors on both drives! I also checked at random locations to see if the data is identical between the drives (sector-for-sector), and it appears to be so. However, I am still unsure if it applies to all data. After all why Control Panel and PowerShell report strange values for % of pool used and storage efficiency?
- I am using Windows 10 1803 x64 Professional
Here's other relevant info:
PassThroughClass : PassThroughIds : PassThroughNamespace : PassThroughServer : Access : Read/Write AllocatedSize : 4049885724672 AllocationUnitSize : 268435456 ColumnIsolation : PhysicalDisk DetachedReason : None FaultDomainAwareness : PhysicalDisk FootprintOnPool : 8100576755712 FriendlyName : SS1 HealthStatus : Warning Interleave : 262144 IsDeduplicationEnabled : False IsEnclosureAware : False IsManualAttach : False IsSnapshot : False IsTiered : False LogicalSectorSize : 4096 MediaType : Unspecified Name : NameFormat : NumberOfAvailableCopies : NumberOfColumns : 1 NumberOfDataCopies : 2 NumberOfGroups : 1 OperationalStatus : OK OtherOperationalStatusDescription : OtherUsageDescription : ParityLayout : PhysicalDiskRedundancy : 1 PhysicalSectorSize : 4096 ProvisioningType : Thin ReadCacheSize : 0 RequestNoSinglePointOfFailure : False ResiliencySettingName : Mirror Size : 5992553119744 UniqueIdFormat : Vendor Specific UniqueIdFormatDescription : Usage : Data WriteCacheSize : 0
Any help would be appreciated. Thanks.