public static void MoveExtentDataRight(Volume volume, DiskExtent sourceExtent, DiskExtent relocatedExtent, MoveExtentOperationResumeRecord resumeRecord, ref long bytesCopied)
{
// we make sure no data will be overwritten too soon:
long distanceLBA = (long)(resumeRecord.NewStartSector - resumeRecord.OldStartSector);
bool bufferedMode = false;
if (distanceLBA < BufferedModeThresholdLBA)
{
bufferedMode = true;
}
int transferSizeLBA;
if (bufferedMode)
{
transferSizeLBA = (int)resumeRecord.BackupBufferSizeLBA;
}
else
{
transferSizeLBA = (int)Math.Min(Settings.MaximumTransferSizeLBA, distanceLBA);
}
// move the data
for (long readCount = (long)resumeRecord.NumberOfCommittedSectors; readCount < relocatedExtent.TotalSectors; readCount += transferSizeLBA)
{
// we read (and write) from the end of the extent and progress to the left
long sectorsLeft = relocatedExtent.TotalSectors - readCount;
int sectorsToRead = (int)Math.Min(transferSizeLBA, sectorsLeft);
long sectorIndex = relocatedExtent.TotalSectors - readCount - sectorsToRead;
byte[] data = sourceExtent.ReadSectors(sectorIndex, sectorsToRead);
if (bufferedMode)
{
// we write the data to the buffer for recovery purposes
relocatedExtent.Disk.WriteSectors((long)resumeRecord.BackupBufferStartSector, data);
resumeRecord.RestoreFromBuffer = true;
// Note: if the extent we move is the first in the volume, we will write the resume record to
// the source extent, which is the one that the database is still referring to
volume.WriteSectors(0, resumeRecord.GetBytes(volume.BytesPerSector));
}
relocatedExtent.WriteSectors(sectorIndex, data);
// update the resume record
resumeRecord.RestoreFromBuffer = false;
resumeRecord.NumberOfCommittedSectors += (ulong)sectorsToRead;
volume.WriteSectors(0, resumeRecord.GetBytes(volume.BytesPerSector));
bytesCopied = (long)resumeRecord.NumberOfCommittedSectors * sourceExtent.BytesPerSector;
}
}
public static void MoveExtentDataLeft(Volume volume, DiskExtent sourceExtent, DiskExtent relocatedExtent, MoveExtentOperationResumeRecord resumeRecord, ref long bytesCopied)
{
// we make sure no data will be overwritten too soon:
long distanceLBA = (long)(resumeRecord.OldStartSector - resumeRecord.NewStartSector);
bool bufferedMode = false;
if (distanceLBA < BufferedModeThresholdLBA)
{
bufferedMode = true;
}
int transferSizeLBA;
if (bufferedMode)
{
transferSizeLBA = (int)resumeRecord.BackupBufferSizeLBA;;
}
else
{
transferSizeLBA = (int)Math.Min(Settings.MaximumTransferSizeLBA, distanceLBA);
}
// move the data
for (long sectorIndex = (long)resumeRecord.NumberOfCommittedSectors; sectorIndex < relocatedExtent.TotalSectors; sectorIndex += transferSizeLBA)
{
long sectorsLeft = relocatedExtent.TotalSectors - sectorIndex;
int sectorsToRead = (int)Math.Min(transferSizeLBA, sectorsLeft);
byte[] data = sourceExtent.ReadSectors(sectorIndex, sectorsToRead);
if (bufferedMode)
{
// we write the data to the buffer for recovery purposes
relocatedExtent.Disk.WriteSectors((long)resumeRecord.BackupBufferStartSector, data);
resumeRecord.RestoreFromBuffer = true;
relocatedExtent.WriteSectors(0, resumeRecord.GetBytes(relocatedExtent.BytesPerSector));
}
relocatedExtent.WriteSectors(sectorIndex, data);
// update the resume record
resumeRecord.RestoreFromBuffer = false;
resumeRecord.NumberOfCommittedSectors += (ulong)sectorsToRead;
volume.WriteSectors(0, resumeRecord.GetBytes(volume.BytesPerSector));
bytesCopied = (long)resumeRecord.NumberOfCommittedSectors * sourceExtent.BytesPerSector;
}
}
/// <summary>
/// Move extent to a new location on the same disk
/// </summary>
public static void MoveExtentWithinSameDisk(DiskGroupDatabase database, DynamicVolume volume, DynamicDiskExtent sourceExtent, DiskExtent relocatedExtent, ref long bytesCopied)
{
MoveExtentOperationResumeRecord resumeRecord = new MoveExtentOperationResumeRecord();
// 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 = PrivateRegionHelper.FindUnusedSector(dynamicDisk.PrivateHeader, dynamicDisk.TOCBlock);
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 = (long)Math.Abs((double)resumeRecord.NewStartSector - resumeRecord.OldStartSector);
if (distanceLBA < MoveHelper.BufferedModeThresholdLBA)
{
long backupBufferStartSector = PrivateRegionHelper.FindUnusedRegion(dynamicDisk.PrivateHeader, dynamicDisk.TOCBlock, 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(volume.BytesPerSector));
if (sourceExtent.FirstSector < relocatedExtent.FirstSector)
{
// move right
MoveExtentRight(database, 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(relocatedExtent.BytesPerSector));
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(database.Disks, volume.VolumeGuid);
MoveExtentLeft(database, volume, resumeRecord, ref bytesCopied);
}
}