public static void AddDiskToRaid5Volume(DiskGroupDatabase database, Raid5Volume volume, DiskExtent newExtent, ref long bytesCopied)
{
// If there will be a power failure during the conversion, our RAID volume will resync during boot,
// To prevent destruction of the data, we temporarily convert the array to striped volume
VolumeManagerDatabaseHelper.ConvertRaidToStripedVolume(database, volume.VolumeGuid);
ulong newExtentID = VolumeManagerDatabaseHelper.AddNewExtentToVolume(database, volume, newExtent);
// Backup the first sector of the first extent to the last sector of the new extent
// (We replace the filesystem boot record with our own sector for recovery purposes)
byte[] filesystemBootRecord = volume.Extents[0].ReadSector(0);
newExtent.WriteSectors(newExtent.TotalSectors - 1, filesystemBootRecord);
AddDiskOperationResumeRecord resumeRecord = new AddDiskOperationResumeRecord();
resumeRecord.VolumeGuid = volume.VolumeGuid;
PrivateHeader privateHeader = PrivateHeader.ReadFromDisk(newExtent.Disk);
// privateHeader cannot be null at this point
resumeRecord.NumberOfCommittedSectors = 0;
// we use volume.WriteSectors so that the parity information will be update
// this way, we could recover the first sector of each extent if a disk will fail
volume.WriteSectors(0, resumeRecord.GetBytes(volume.BytesPerSector));
ResumeAddDiskToRaid5Volume(database, volume, new DynamicDiskExtent(newExtent, newExtentID), resumeRecord, ref bytesCopied);
}
/// <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);
}
}
