Thursday, May 13, 2010

Disk Utility Live Verification Fails on Unmountable Mac OS X Volumes

Hard drive inconsistency and integrity problems are very common in Mac OS X operating system. To handle such problems up to an extent, Mac OS X operating system provides you an inbuilt tool, called Disk Utility. It verifies your hard drive and repairs the damages in some situations. The utility can be run from boot disk of Mac OS X operating system. You can run this program even on the live hard drive. This process is known as Live Verification.

However, in some situations, Live Verification of Mac hard drive may cause serious problems that lead to hard drive failure and data loss. At this point of time, you need to go for Mac Data Recovery solutions, if there is no valid backup in place.

You should keep the below things in mind while performing a Live Verification of Mac OS X had drive:

• The Live Verification works only on Journaled volumes of HFS+ file system. If you try it on non-journaled volumes, you may get an error message stating: “ERROR: could not freeze volume (Operation not supported).”

• The progress indicator of Disk Utility might stop advancing, applications may become unresponsive or work slow, or your system may freeze during Live Verification.

• Once you initialize the Live Verification process, you may not abort it.

• You may come across some problem when you attempt to repair or verify a unmountable Mac volume.

What happens when you run Live Verification on unmountable Mac volume?

Disk Utility program may freeze without showing any error, or stall the machine for few minutes, while repairing or verifying the unmountable volume.

When you attempt to verify a non-startup volume and Disk Utility cannot unmount it for any reason, verification process may start, but and may stop without any error.

After this behavior of Disk Utility and your Mac OS X system, the drive remains in inconsistent and damaged state. You cannot access data from such drive and need to perform Data Recovery Mac by resolving this issue.

You can easily recover your valuable data using Mac recovery software as they have interactive graphical user interface. The Mac data recovery applications employ high-end scanning techniques to thoroughly scan entire hard drive and extract all lost data from it.

Stellar Phoenix Macintosh Data Recovery is the most efficient and comprehensive utility that ensures absolute recovery in all data loss scenarios. The software safely recovers lost data from HFS, HFS+, HFSX, HFS Wrapper, and FAT file system volumes. It is usable with Mac OS X 10.6 Snow Leopard, 10.5 Leopard, 10.4 Tiger, and 10.3.9 Panther.

Tuesday, May 11, 2010

Catalog File Corruption and Mac OS X Error

Like every operating system Mac OS X-based hard disk is also divided into different volumes. Each volume is comprised of four basic items: files, file threads, directories and directory threads. To define these items, Mac volumes keep their records in the form of catalog file. This catalog file is structured in B*-tree formation. Thus to locate a file or directory, system has to traverse whole catalog B*-tree.

But sometimes, this tree or its nodes can suffer issues, which may require reformatting the volume. In such cases, you are suggested to take full data backup so as to restore it later. In case of backup faults, Mac Recovery solutions are required. User may observe an error with Mac volumes:

“Invalid B-tree node size”

This error is observed with Hierarchical file system based volumes while verifying its integrity using Disk Utility. Damaged volume fails to be repaired using Disk Utility. The error is encountered if node size of B-tree is not correct. Note: The allowed size for records in HFS Catalog file is 512 bytes and in HFS Plus Catalog file is 8 KB.

To resolve the issue, you can try these solutions:

Disk Utility fails to correct invalid node size of B-tree. Thus, you can run fsck. It should be used in single user mode.

You can also use third-party disk repair applications. Such applications can cause more damages, so it is suggested to maintain a copy of all data, prior to use these applications.

If problem remains the same, you can backup all important data and perform clean reinstallation of Mac OS X. It can be carried out using Erase and Install option. Also, data backup must be valid enough to offer complete restoration.

Thus after backup process, the log reports and media must be checked. If data backup proves invalid to give required files, you can use commercial Data Recovery Mac tools. Mac Recovery applications scan media, in question, and recover lost data. These software products offer safe recovery with advanced searching options.

The procedures are safe. Such applications perform suitable file searching processes, irrespective of file system metadata. Thus, you can use these tools in any case logical data loss case. Macintosh Data Recovery is advanced Data Recovery Mac software for HFS, HFS+, HFSX, HFS Wrapper and FAT file system based disks. It uses influential and secure scanning algorithms.

Monday, May 10, 2010

HFS+ File System Corruption and Recovery

Mac OS X has a number file types like HFS, HFS+, and HFSX, among all HFS+ is the improved version of Mac OS Standard, HFS. HFS Plus volumes are comprised of different metadata structure information like Volume Header, Catalog File, and Allocation File etc., defined on their various sectors. Volume Header is the replacement of Master Directory Block of HFS volumes and stores volume metadata.

But due to corruption or inconsistencies in one or more metadata information, HFS+ volumes may get damaged. In such cases, data gets inaccessible and hence users may require HFS Data Recovery tools to recover (if data backup is unavailable, incomplete or damaged). As a scenario, when Mac OS X users attempt to boot the system or access one of the HFS Plus partition, an error is encountered:

“HFS+ partition Error”

This error is generally observed on dual-boot systems, more often with GRUB. System fails to boot when the affected volume is startup volume.

To solve this partition error, users can follow up given solutions:

User can use fsck and Disk Utility to repair the damaged volume

If GRUB is creating issue, user can check for its correct installation

If problem persists, partitioning scheme can be the concern. HFS Plus partitions use APM (Apple Partition Map) as their partitioning scheme. Particularly, incorrect starting sector number (odd number) of partition can create such errors.

Thus, it is required to repartition the disk and restore data from recent backup. If data backup is unavailable or incomplete, HFS Recovery applications come as rescue to recover lost information.

These applications search the affected drive for lost data and restore it securely. Mac Recovery software are the specialized tools to scan the drives and recover lost information. These applications make file system and operating system level scanning. Upon finding lost files, these solutions recover them.

Most of these applications come with interactive user interface, enriched with graphic tools and options. Hence, irrespective of any level of technical background, users can use them quite easily. These software products are safe to be used because of read-only design they possess.