Reading MTF Backup Files

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Introduction

We use the NTBackup utility to backup our files at the office. Recently, one of the backup files turned out to be corrupt. Searcing for a solution, I came upon William T. Kranz's freeware ntbkup utility. Although ntbkup did a great job recovering the backup file, it is a command line utility. So, I decided to write a backup reader with a GUI.

Background

Volume, file, and folder information in a MTF backup file is stored as so called Descriptor Blocks. MTF is a linear file format. Reading a MTF backup file is a straightforward process. A backup file contains Data Set Descriptor Blocks, which are followed by Volume Descriptor Blocks. Volume Descriptor Blocks are followed by Directory Descriptor Blocks, which are in turn followed by File Descriptor Blocks.

Each descriptor block is followed by one or more Data Streams. Data streams are used for various purposes. They can be used for padding, storing checksums, long file/folder names, etc. One or more data streams associated with a file descriptor block typically contain file data.

Using the code

To read a backup file, an implementation creates a new instance of the CBackupReader class, passing the name of the backup file as an argument. Then, a catalog is created using the CCatalogNode class. The CCatalogNode class has a tree structure. The root of the tree is the backup file itself. Its child nodes represent the data sets in the backup file. Each data set node contains one (and only one) volume node. Volume nodes contain folders and files as child nodes. To extract a file from the catalog, one traverses the tree to reach the file and calls the ExtractTo method of the CCatalogNode class.

// Open the backup file

CBackupReader mFile = new CBackupReader(mFileName);
// Read the catalog

CCatalogNode node = mFile.ReadCatalog();
// Extract a node from the catalog

node.ExtractTo(mFile, mTargetPath); 

Limitations

• Backup Reader was tested with a few relatively small backup files. The largest backup file tested was about 2 GB.
• Compressed and encrypted archives are not supported.
• Backup Reader works on Windows archives only. Although descriptor block definitions for other operating systems are included in the source code, they are not tested.
• Archives that span multiple tapes/disks are not supported.

References

1. ntbkup - William T. Kranz's freeware backup utility
2. MTF specification and a Linux backup reader with C source code

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error to compile icelso2006 13:18 6 Oct '07   I tried to compile and receive the following error: "Exception System.IndexOutOfRangeException was thrown in debuggee: Index was outside the bounds of the array. SetKeyName() InitializeComponent() - e:\util\BackupReader_src\BackupReader\frmMain.Designer.cs:117,13 .ctor() - e:\util\BackupReader_src\BackupReader\frmMain.cs:18,13 Main() - e:\util\BackupReader_src\BackupReader\Program.cs:17,13" I'm using the .NET framework 3.0, Win XP sp2 SharpDevelop compiler Any suggestion? Or anybody has the executable? Sign In·View Thread·PermaLink 1.00/5 (1 vote) Any help will be appreciated SaeidehV 23:34 30 Sep '07   I’m using ntbackup.exe as a process in my application to backup some files and then your class for restoring the data. Everythibg is ok if I run my application(in C#) from my hard disks, but I have to deploy my application on flash memoty And when I run my application from the flash memory ntbackup.exe works well and backups the files successfully but after finishing the backup process my application does not work properly and I got this error from different part of my application ( when I want to show a new form in the form initializecomponent() method) ************** Exception Text ************** System.Runtime.InteropServices.SEHException: External component has thrown an exception. at System.IO.UnmanagedMemoryStream.ReadByte() at System.IO.BinaryReader.ReadByte() at System.IO.BinaryReader.Read7BitEncodedInt() at System.Resources.ResourceReader.LoadObjectV2(Int32 pos, ResourceTypeCode& typeCode) at System.Resources.ResourceReader.LoadObject(Int32 pos, ResourceTypeCode& typeCode) at System.Resources.RuntimeResourceSet.GetObject(String key, Boolean ignoreCase, Boolean isString) at System.Resources.RuntimeResourceSet.GetObject(String key, Boolean ignoreCase) at System.Resources.ResourceManager.GetObject(String name, CultureInfo culture, Boolean wrapUnmanagedMemStream) at System.Resources.ResourceManager.GetObject(String name, CultureInfo culture) at BaseMVC.BaseMVCResource.get_View() at BaseMVC.Browser.BrowserFrm.InitializeComponent() I searched a lot but I could not find a solution (even I wrote the Application.DoEvents() in my code but it does not work) I’d be thankful if you can guid me? FYI,I copied the ntbackup.exe on my flashdisk and it does not work properly there either ?! Thanks in advance, Saeideh Sign In·View Thread·PermaLink SQL MTF DanielSass 5:30 2 Sep '07   Hi, Can I use this code to read SQL SERVER BACKUP Files (*.bck)? Does MTF for SQL BACKUP Files is the same MTF for NTbackup utility? Is there any simple way to change the above code for reading SQL Backup MTF files? Thnks! DS Sign In·View Thread·PermaLink Re: SQL MTF Ozgur Ozcitak 21:58 13 Sep '07   I have no idea. Perhaps this article might be of help: SQL Server backup utility Sign In·View Thread·PermaLink license ? seb9000 6:54 25 Jul '07   What is the license type of this project ? Sign In·View Thread·PermaLink Re: license ? Ozgur Ozcitak 4:45 1 Aug '07   You are free to use/modify/distribute it in whatever way you like. But, if you are going to use it in a real world application, I suggest that you fix the file extraction code. As discussed below, it may lead to bugs/performance issues. Sign In·View Thread·PermaLink Possible Bug winki_ 5:49 14 May '07   hi look at the contructor of CDataStream. you cast Header.StreamLength to an int value which can lead to a bug. Data = Reader.ReadBytes((int)Header.StreamLength); Sign In·View Thread·PermaLink Re: Possible Bug Ozgur Ozcitak 2:13 6 Jun '07   Right. Header.StreamLength is an unsigned long. I am using a BinaryReader which can handle data up to 2 GB if I recall correctly. If the file data is larger than that, it will certainly cause a bug. Actually, reading the entire file data into memory is not a good idea at all. This part of the code requires a major revision. Instead of reading the entire file, I should probably just get the offset to file data, and write that data to disk when required. Thanks for pointing that out. I will fix that in a future release when I have some free time. Sign In·View Thread·PermaLink 1.00/5 (1 vote) Merhaba [modified] bukos 14:12 21 Apr '07   Öncellikle Türkçe yazdığım için kusura bakma. Yazdığın program gerçekten çok işime yaradı. Yanlız System State (Domain Controller) yedeğini okurken %91'de devamlı takılıyor. Bu konu hakkına birseyler yapabilirmisin? -- modified at 8:04 Tuesday 24th April, 2007 Sign In·View Thread·PermaLink Re: Merhaba Ozgur Ozcitak 1:39 3 May '07   Kendi bilgisayarimda denedigimde System State yedegini sonuna kadar okudu. Debug ederek nerede ve neden takildigini soyleyebilir misin? Sign In·View Thread·PermaLink Re: Merhaba bukos 11:21 3 May '07   Tekrar Merhaba, Windows 2003 Active Directory backup'ını okurken "Active Directory" , "SYSVOL" ve "registery" kayıtlarını okumuyor. Yazılımcı bir arkadaşım bu yukarıda bahsettiğim dizinlerle ilgili programda tanımlama yapılmadığını ve bu yüzden reader okurken bu kayıtlara gelince takıldığını soyluyor. Normal system state bkf dosylarını reader okuyor ve extract edebiliyor. Sanki Active directory ile ilgili block type'lar eksik gibi. Debug yatım ve cbackupstream.cs EBlockType et = (EBlockType)ReadUInt32(); da takılıyor gibi. Okuması gereken block'lar Active Directory Boot Files COM+ Class Registration Database Registery SYSVOL Sign In·View Thread·PermaLink Reverse action code ? dss.manager 1:12 9 Apr '07   The sample code was useful. How will it be good to implement backup of a file? Sign In·View Thread·PermaLink Re: Reverse action code ? ozgurozcitak 6:06 9 Apr '07   I wrote this utility to recover some corrupt backup files. Writing backup files was not a goal. I may look into that in the future if I have the time. Sign In·View Thread·PermaLink 2.00/5 (1 vote) Many Thanks! CrnlJohnSmith 16:06 28 Mar '07   Excellant Code! Just what I needed! Sign In·View Thread·PermaLink thanks for this nice tool. volkan.ozcelik 6:18 22 Mar '07   Thanks Ozgur for this utility, I was looking for something similar that traverses inside the backup files etc. And your article came just-in-time for me. Cheers, .: linkibol - in seek of quality links bullishly :. my blog on coding, humor and creativity .: my trials/errors/studies :. sardalya AJAX Framework Sign In·View Thread·PermaLink 2.00/5 (1 vote) Re: thanks for this nice tool. ozgurozcitak 4:28 27 Mar '07   I am glad you found it useful. Cheers, Ozgur Sign In·View Thread·PermaLink 2.00/5 (1 vote)

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