-
Title
Volume Offset or Disk Misalignment Errors -
Description
Backups will not complete on one or more protected volumes. One of the following errors is observed:"Transmission of snapshot data failed. Check the AppAssure event log on the Replay Core for more details. - The drive cannot find the sector requested""Replay.Common.Contracts.Win32Api.Win32ApiFailedException: I/O operation - The drive cannot find the sector requested""Network Error transferring the Volume""The agent lost connection during the transfer""ERROR [18] - Replay.Agent.Implementation.Transfer.TransferDataChannel (RemoteEndPoint=xxxx:63253)Sending of volume data at byte offset 0xd4ad48a000, byte length 0x400000 failedSystem.AggregateException: One or more errors occurred. ---> Replay.Common.Contracts.Win32Api.Win32ApiFailedException: I/O operation - The system cannot find the file specified""ERROR [195] - Replay.Agent.Implementation.Transfer.TransferDataChannel (RemoteEndPoint=xxxx:64897)Sending of volume data at byte offset 0xb587730000, byte length 0x8000 failedSystem.AggregateException depth 0: One or more errors occurred. (0x80131500) ---> (Inner Exception #0 depth 0) Replay.Common.Contracts.Win32Api.Win32ApiFailedException depth 1: I/O operation - The specified network name is no longer available (0x80131500)at Replay.Common.Implementation.Win32Api.NativeIOReader.EndTransmitFile(IAsyncResult asyncResult)" -
Cause
The described problem may be related to a misaligned disk. Partition misalignment can cause volume offset errors with backups and virtual machine (VM) exports. It can also caused Bare-Metal Restores to hang. The following section details the steps necessary to verify whether or not your partitions are aligned and, if not, how to correct them. -
Resolution
Solution A:
You may want to check the disk for errors - Run CHKDSK /R until all errors are resolved if any.
Solution B:
Identify disk misalignment
1) On the server which will not protect a volume run the command msinfo32 from a Command Prompt
2) Within the MSINFO32 Browse to Components | Storage | Disks
3) For the disk containing the volume that will not snapshot - Note the overall disk size - (299,966,300,160 bytes in the example screenshot above)
4) Add the Partition Starting offset of the first partition (1,048,576) and the individual partition sizes of the partitions on the disk (104,857,600 and 299,958,462,464 bytes)
5) Compare the figure from step 3 with the figure from step 4
6) In this example:
1,048,576 + 104,857,600 + 299,958,462,464 = 300,064,368,640 - which is larger than the actual disk total size of 299,966,300,160 bytes. This indicates misalignment on the disk
7) Subtract the total disk size 299,966,300,160 from the combined partition sizes (300,064,368,640) = 98068480 bytes.
8) Convert 98068480 bytes to MB gives a figure of 93.52 MB
Shrink Identified Misaligned volumes1) Open Diskmgmt.msc
2) Right click the volume that is failing in protection and choose Shrink Volume
3) Shrink the volume by the value appropriately larger than from the previous step 8 (eg. 100MB)
4) Following completion of the disk shrink test the snapshot again