private static void ClearBackupData(Disk relocatedExtentDisk, MoveExtentOperationBootRecord resumeRecord)
{
byte[] emptySector = new byte[relocatedExtentDisk.BytesPerSector];
relocatedExtentDisk.WriteSectors((long)resumeRecord.BootRecordBackupSector, emptySector);
if (resumeRecord.BackupBufferStartSector > 0)
{
byte[] emptyRegion = new byte[resumeRecord.BackupBufferSizeLBA * relocatedExtentDisk.BytesPerSector];
relocatedExtentDisk.WriteSectors((long)resumeRecord.BackupBufferStartSector, emptyRegion);
}
}
/// <summary>
/// Move extent to a new location on the same disk
/// </summary>
public static void MoveExtentWithinSameDisk(List<DynamicDisk> disks, DynamicVolume volume, DynamicDiskExtent sourceExtent, DiskExtent relocatedExtent, ref long bytesCopied)
{
DiskGroupDatabase database = DiskGroupDatabase.ReadFromDisks(disks, volume.DiskGroupGuid);
if (database == null)
{
throw new DatabaseNotFoundException();
}
MoveExtentOperationBootRecord resumeRecord = new MoveExtentOperationBootRecord();
// If there will be a power failure during the move, a RAID volume will resync during boot,
// To prevent destruction of the data, we temporarily convert the array to striped volume
if (volume is Raid5Volume)
{
VolumeManagerDatabaseHelper.ConvertRaidToStripedVolume(database, volume.VolumeGuid);
resumeRecord.RestoreRAID5 = true;
}
// We want to write our own volume boot sector for recovery purposes, so we must find where to backup the old boot sector.
// We don't want to store the backup in the range of the existing or relocated extent, because then we would have to move
// the backup around during the move operation, other options include:
// 1. Store it between sectors 1-62 (cons: Could be in use, Windows occasionally start a volume from sector 1)
// 2. Find an easily compressible sector (e.g. zero-filled) within the existing extent, overwrite it with the backup, and restore it when the operation is done.
// 3. use the LDM private region to store the sector.
DynamicDisk dynamicDisk = DynamicDisk.ReadFromDisk(relocatedExtent.Disk);
// Note: backupSectorIndex will be from the beginning of the private region while backupBufferStartSector will be from the end
// so there is no need to allocate them
long backupSectorIndex = DynamicDiskHelper.FindUnusedSectorInPrivateRegion(dynamicDisk);
resumeRecord.VolumeGuid = volume.VolumeGuid;
resumeRecord.NumberOfCommittedSectors = 0;
resumeRecord.ExtentID = sourceExtent.ExtentID;
resumeRecord.OldStartSector = (ulong)sourceExtent.FirstSector;
resumeRecord.NewStartSector = (ulong)relocatedExtent.FirstSector;
resumeRecord.BootRecordBackupSector = (ulong)backupSectorIndex;
long distanceLBA = Math.Abs((long)resumeRecord.NewStartSector - (long)resumeRecord.OldStartSector);
if (distanceLBA < MoveHelper.BufferedModeThresholdLBA)
{
long backupBufferStartSector = DynamicDiskHelper.FindUnusedRegionInPrivateRegion(dynamicDisk, BackupBufferSizeLBA);
if (backupBufferStartSector == -1)
{
throw new Exception("Private region is full");
}
if (backupBufferStartSector <= backupSectorIndex)
{
throw new Exception("Private region structure is unknown");
}
resumeRecord.BackupBufferStartSector = (ulong)backupBufferStartSector;
resumeRecord.BackupBufferSizeLBA = BackupBufferSizeLBA;
}
// Backup the first sector of the first extent
// (We replace the filesystem boot record with our own sector for recovery purposes)
byte[] filesystemBootRecord = volume.ReadSector(0);
relocatedExtent.Disk.WriteSectors(backupSectorIndex, filesystemBootRecord);
// we write the resume record instead of the boot record
volume.WriteSectors(0, resumeRecord.GetBytes());
if (sourceExtent.FirstSector < relocatedExtent.FirstSector)
{
// move right
MoveExtentRight(disks, volume, resumeRecord, ref bytesCopied);
}
else
{
// move left
// we write the resume record at the new location as well (to be able to resume if a power failure will occur immediately after updating the database)
relocatedExtent.WriteSectors(0, resumeRecord.GetBytes());
DynamicDiskExtent dynamicRelocatedExtent = new DynamicDiskExtent(relocatedExtent, sourceExtent.ExtentID);
dynamicRelocatedExtent.Name = sourceExtent.Name;
dynamicRelocatedExtent.DiskGuid = sourceExtent.DiskGuid;
VolumeManagerDatabaseHelper.UpdateExtentLocation(database, volume, dynamicRelocatedExtent);
int extentIndex = DynamicDiskExtentHelper.GetIndexOfExtentID(volume.DynamicExtents, sourceExtent.ExtentID);
// get the updated volume (we just moved an extent)
volume = DynamicVolumeHelper.GetVolumeByGuid(disks, volume.VolumeGuid);
MoveExtentLeft(disks, volume, resumeRecord, ref bytesCopied);
}
}
private static void MoveExtentRight(List<DynamicDisk> disks, DynamicVolume volume, MoveExtentOperationBootRecord resumeRecord, ref long bytesCopied)
{
DiskGroupDatabase database = DiskGroupDatabase.ReadFromDisks(disks, volume.DiskGroupGuid);
if (database == null)
{
throw new DatabaseNotFoundException();
}
int extentIndex = DynamicDiskExtentHelper.GetIndexOfExtentID(volume.DynamicExtents, resumeRecord.ExtentID);
DynamicDiskExtent sourceExtent = volume.DynamicExtents[extentIndex];
DiskExtent relocatedExtent = new DiskExtent(sourceExtent.Disk, (long)resumeRecord.NewStartSector, sourceExtent.Size);
MoveHelper.MoveExtentDataRight(volume, sourceExtent, relocatedExtent, resumeRecord, ref bytesCopied);
// even if the database update won't complete, the resume record was copied
// update the database
DynamicDiskExtent dynamicRelocatedExtent = new DynamicDiskExtent(relocatedExtent, sourceExtent.ExtentID);
dynamicRelocatedExtent.Name = sourceExtent.Name;
dynamicRelocatedExtent.DiskGuid = sourceExtent.DiskGuid;
VolumeManagerDatabaseHelper.UpdateExtentLocation(database, volume, dynamicRelocatedExtent);
// if this is a resume, then volume is StripedVolume, otherwise it is a Raid5Volume
if (resumeRecord.RestoreRAID5)
{
VolumeManagerDatabaseHelper.ConvertStripedVolumeToRaid(database, volume.VolumeGuid);
}
// get the updated volume (we moved an extent and possibly reconverted to RAID-5)
volume = DynamicVolumeHelper.GetVolumeByGuid(disks, volume.VolumeGuid);
// restore the filesystem boot sector
byte[] filesystemBootRecord = relocatedExtent.Disk.ReadSector((long)resumeRecord.BootRecordBackupSector);
volume.WriteSectors(0, filesystemBootRecord);
ClearBackupData(relocatedExtent.Disk, resumeRecord);
}
private static void MoveExtentLeft(List<DynamicDisk> disks, DynamicVolume volume, MoveExtentOperationBootRecord resumeRecord, ref long bytesCopied)
{
DiskGroupDatabase database = DiskGroupDatabase.ReadFromDisks(disks, volume.DiskGroupGuid);
if (database == null)
{
throw new DatabaseNotFoundException();
}
DynamicDiskExtent relocatedExtent = DynamicDiskExtentHelper.GetByExtentID(volume.DynamicExtents, resumeRecord.ExtentID);
if (resumeRecord.OldStartSector == (ulong)relocatedExtent.FirstSector)
{
// the database update was not completed (this must be a resume operation)
relocatedExtent = new DynamicDiskExtent(relocatedExtent.Disk, (long)resumeRecord.NewStartSector, relocatedExtent.Size, resumeRecord.ExtentID);
VolumeManagerDatabaseHelper.UpdateExtentLocation(database, volume, relocatedExtent);
}
DiskExtent sourceExtent = new DiskExtent(relocatedExtent.Disk, (long)resumeRecord.OldStartSector, relocatedExtent.Size);
MoveHelper.MoveExtentDataLeft(volume, sourceExtent, relocatedExtent, resumeRecord, ref bytesCopied);
// if this is a resume, then volume is StripedVolume, otherwise it is a Raid5Volume
if (resumeRecord.RestoreRAID5)
{
VolumeManagerDatabaseHelper.ConvertStripedVolumeToRaid(database, volume.VolumeGuid);
// get the updated volume (we just reconverted to RAID-5)
volume = DynamicVolumeHelper.GetVolumeByGuid(disks, volume.VolumeGuid);
}
// restore the filesystem boot sector
byte[] filesystemBootRecord = relocatedExtent.Disk.ReadSector((long)resumeRecord.BootRecordBackupSector);
volume.WriteSectors(0, filesystemBootRecord);
ClearBackupData(relocatedExtent.Disk, resumeRecord);
}
public static void ResumeMoveExtent(List<DynamicDisk> disks, DynamicVolume volume, MoveExtentOperationBootRecord resumeRecord, ref long bytesCopied)
{
if (resumeRecord.OldStartSector == resumeRecord.NewStartSector)
{
throw new InvalidDataException("Invalid move record");
}
if (resumeRecord.RestoreFromBuffer)
{
// we need to use the backup buffer to restore the data that may have been overwritten
int extentIndex = DynamicDiskExtentHelper.GetIndexOfExtentID(volume.DynamicExtents, resumeRecord.ExtentID);
DynamicDiskExtent sourceExtent = volume.DynamicExtents[extentIndex];
byte[] backupBuffer = sourceExtent.Disk.ReadSectors((long)resumeRecord.BackupBufferStartSector, BackupBufferSizeLBA);
if (resumeRecord.OldStartSector < resumeRecord.NewStartSector)
{
// move right
long readCount = (long)resumeRecord.NumberOfCommittedSectors;
int sectorsToRead = BackupBufferSizeLBA;
long sectorIndex = sourceExtent.TotalSectors - readCount - sectorsToRead;
sourceExtent.WriteSectors(sectorIndex, backupBuffer);
System.Diagnostics.Debug.WriteLine("Restored to " + sectorIndex);
}
else
{
// move left
long sectorIndex = (long)resumeRecord.NumberOfCommittedSectors;
sourceExtent.WriteSectors(sectorIndex, backupBuffer);
System.Diagnostics.Debug.WriteLine("Restored to " + sectorIndex);
}
}
if (resumeRecord.OldStartSector < resumeRecord.NewStartSector)
{
MoveExtentRight(disks, volume, resumeRecord, ref bytesCopied);
}
else
{
MoveExtentLeft(disks, volume, resumeRecord, ref bytesCopied);
}
}