Stellar Partition Manager for Mac OS X

“I have recently ungraded to an Intel-based Mac machine, but Mac Lion is not booting now. How can I make my Mac running again? I am not much familiar with its internal utilities. Do I need to delete and rebuild every Mac volume? Somebody please let me know how to do it.”

In addition to all disk-related activities (e.g. disk verify and repair), Disk Utility facilitates you to format Mac hard drive and rebuild Mac volumes safely. However, those who are newbie may not be aware of how to repartition Mac drive. Refer to the scenario discussed above representing a repartitioning issue on dissimilar Mac machines. However, the difference between an Intel-based Mac machine (GPT – GUID Partition Table) and a PowerPC-based Mac machine (APM – Apple Partition Table) is the Partition Map Scheme.

An Intel-based Mac can read/write the data on APM partitions, but cannot boot from it. Similarly, a PowerPC-base Mac can read/write the data on GPT partitions, but cannot boot from it. Therefore, you have to format Mac drive to change the Partition Map Scheme to GPT. Following are quick and safe tips to partition Mac drive after deleting all volumes on an Intel-based Mac machine.

• Attach your hard drive to a running Intel-based Mac machine (or if your Mac machine has multiple hard drives installed on it, boot from another one).
• Launch Disk Utility from Applications/Utilities/Disk Utility.
  Select the target hard drive shown in the left pane of the Disk Utility window and simultaneously go to Partition tab in the right pane. Here, under Volume Scheme area, you will see the graphical structure of the Mac drive partitioned into several volumes.
  Click a Volume, and then click minus (-) button to delete it. The space freed up after deleting a volume is displayed at the end of last partition. Now, repeat the process for each Mac volume and free up overall memory. This will result in a single partition containing all the space on the drive.
• Click Options button below drive structure, and choose GUID Partition Table as the Partition Map Scheme.
• Now, in the dropdown list under Volume Scheme area, choose how many partitions you need to create on the Mac drive. If you select 4 partitions, the drive memory will be divided into 4 partitions of equal sizes. However, you can resize them again.
• Specify a name and choose a format for every Mac volume individually. After the partitions are created, click Apply to save the modifications done so far. Click Partition button on the message displayed. After the processing is finished, a new drive will be displayed on the desktop.
• Now, run Mac boot disc and install OS X on any of the volumes.
  After the installation is finished, boot from this drive on your Intel-based Mac.

You may not find a newly purchased Mac machine meeting all your requirements (such as number of partitions the hard drive is divided into) making you think of repartitioning. Therefore, if you are planning to repartition the Mac hard drive, Disk Utility is the tool you need in order to manage Mac partitions. Moreover, you can also perform several other disk related activities, such as checking the health status of the entire hard drive, or of the volumes individually. If you observe any error or any other difficulty in accessing the data, you should verify and repair disk permissions instantly.

Apart from some typical disk management operations, Disk Utility facilitates creating disk image, creating drive clone, and burning CD/DVD in both GUI and command line mode, i.e. Terminal using “diskutil” command. In Mac, partition management operations include creating, modifying/resizing, and deleting partitions using Disk Utility or any other similar external software you are familiar with; but for now, let us manage Mac partitions with Disk Utility:

Creating new partition
Creating a new partition with Disk Utility is very easy if your disk has free space available, otherwise you have to shrink one or more existing volumes.

To do this, launch Disk Utility (found in Applications > Utilities > Disk Utility) and select the hard drive shown in the left pane. Now, go to the Partition tab in the right pane and select the free space (shown under the last partition) in the graphical view. Now, click plus (+) button to use this space for creating a new partition. Specify a ‘Name’ and choose a ‘Format’ for this partition under Volume Information area. Additionally, you can manually specify its ‘Size’. At last, click Apply to save the changes.

Modifying Existing Partitions
You need to modify existing Mac partitions only if the hard drive is lacking free space. With the help of Disk Utility, you can easily modify one or more Mac partitions (on an Intel-based Mac) using the below discussed procedure:

After selecting the hard drive, go to the Partition tab at the right. In the graphical view of the hard drive, you can see the free space in every existing partition. Click the partition you think you should trim the free space from and drag it upward from its border. Similarly, you can shrink other Mac partitions to create the free space for creating a new one.

Note: You can modify all existing partitions only on an Intel-based Mac. A PowerPC-based Mac does not allow modifying Mac partitions once created.

Deleting a Mac Partition
The easiest and quickest task among partition management operations is to delete a partition. Follow the process mentioned below to delete Mac partition using Disk Utility:

In the partition tab of Disk Utility, select a partition to delete, and click minus (-) button. However, before you delete a partition, make sure it does not have any essential data. Click Apply button to save.
Warning: Once you click Apply button, you cannot undo the changes.
Those who find Disk Utility complex and difficult to work with are recommended to use any external software to perform similar operations.

“I’ve got a new WD 1TB external HDD to install Mac OS X on one partition and to keep all my professional software, data, and office documents on other partitions (categorywise) on my PowerPC-based Mac machine. I really don’t know how to partition a new hard drive.”

The scenario mentioned above is one of the most general partitioning-related issues that Mac users face, either due to inexperience or all of a sudden. However, partitioning a hard drive whether internal or external (does not really matter) in Mac is not as difficult as in Windows. Actually, partitioning Mac drive involves a few steps with Disk Utility, which many Mac users find little bit complex to follow. However, there is nothing like complex in using Disk Utility to perform these disk-related tasks.

Considering the scenario, partitioning a new external HDD on a PowerPC-based Mac machine requires choosing the correct Partition Map Scheme (i.e. Apple Partition Map) out of three (i.e. GUID Partition Table, Apple Partition Map, and Master Boot Record) according to the Processor embedded. Therefore, if you are using an Intel-based Mac machine, you should choose GUID Partition Table; else, choose Apple Partition Map for PowerPC-based Mac machine. Master Boot Record is used to start up Windows and DOS based computers. Refer to the following steps for partitioning Mac drive (external) on PowerPC-based Mac machine:

• Step 1: Attach the HDD to your Mac machine with a USB cable and turn ON its power button (if any).
• Step2: After the HDD is attached to your Mac machine, you will see a Disk Insertion pop-up message. Click Initialize button to let the Disk Utility detect it.
• Step 3: Now launch Disk Utility (Applications/ Utilities folder/ Disk Utility) and select the HDD in the left pane.
• Step 4: Go to the Partition tab in the right pane and choose the number of partitions (from Volume Scheme drop-down list) you want to create on the selected hard drive, e.g. select ‘3 Partitions’ if you want to divide the HDD into 3 partitions of equal sizes. You can resize them afterwards.
• Step 5: Now, click Options button and choose Apple Partition Map in the Partition Map Scheme window, to partition the drive for boot and non-boot partitions on PowerPC-based Mac machine.
• Step 6: Rename the Individual Partitions, choose a Format (Mac OS Extended (Journaled)), and specify a size for manual resizing (optional). Click Apply.

Click Partition button on the warning message box that appears after clicking Apply to save the changes done so far.

Partitioning a hard drive on Mac OS X is not as tricky as in Windows operating systems. Mac allows the user to partition or even repartition a hard drive during and after installation using Disk Utility (a built-in disk management tool). However, those who are beginners with Mac should not try making any change, as it may yield some undesired results. If we see, Mac exhibits graphically pleasing but sophisticated interface that is contrary to that of windows operating system. For example, in case of a beginner, he or she has to find a lot of programs and utilities, which are easily approachable in Windows.

A newly purchased Mac machine may not have several hard drive partitions, but has only i.e. Macintosh HD (boot partition) to save the data. In this situation, those who are not aware of how to trim this only partition and build new ones to store their data may suffer data loss due to OS crash. Disk Utility  includes functionality for all disk related activities, such as creating, resizing, deleting, hiding and revealing hard drive partitions. It also facilitates checking and repairing each Mac volume as well as the permissions associated with them whenever they throw any exception; however, a beginner may not be able to work with it. Therefore, he or she may use Mac partitioning software to proceed with hard drive repartitioning in a better and efficient manner.

Sometimes it becomes necessary to change the number of existing partitions on the drive because you want to install another OS, such as Windows using boot camp or want to keep the OS and data with different categories in separate volumes. Therefore, you need to be familiar with Disk Utility to do it; however, it is suggested not to use Disk Utility to create, modify or delete a Mac partition until or unless you are enough familiar with it.

Disk Utility works on Mac partitions only if they are formatted using GUID Partition Table (GPT) as the Map Scheme, but not if it is either Master Boot Record (MBR) or Apple Partition Map (APM). However, with the help of an efficient Mac partitioning software, a user is able to work on GPT and APM. These software are specially designed for non-professional users (i.e. college students, home users, etc.) who are not proficient in dealing with technically sophisticated operations. Working with such a user-friendly partitioning tool makes the whole process reliable and productive.

Disk Utility in Mac OS X is a smart tool facilitating several disk management tasks, such as resizing, creating and deleting a Mac volume, checking and repairing the disk as well as the set of associated permissions with every individual volume, and more. You can individually image every Mac volume for restoring and accessing it on different Mac machines. When you purchase a Mac machine, you may not find its hard drive already partitioned into several volumes, but the only partition i.e. Macintosh HD (boot volume).

Therefore, you need to resize this boot volume and trim the free available space to create a few other volumes on your hard drive. Though risks are involved in resizing a boot volume in Mac, you can do it successfully using Mac’s inbuilt utilities and some advanced professional software. Let us know the case in which resizing a Mac volume is possible.

Go to Disk Utility (found in Applications-> Utility folder) and select the hard drive in the left pane. You can resize it only if Partition Map Scheme (shown below) is GUID Partition Table (GPT), but not when it is either Apple Partition Map (APM) or Master Boot Record (MBR). You can resize each volume on the Mac machine (matching this criterion), but up to the limit of data stored in it. Area containing the data is shown as locked in the graphical view of the hard drive under partition tab in the Disk Utility window.

Since the criterion under which you can resize a Mac volume is narrow, the involvement of the risk factor can be estimated easily. Resizing a boot volume in Mac may disturb its file system and result in system crash. File system corruption leads to data loss, which certainly is not the desire of a user. Therefore, if you still need to resize the boot volume on your Mac machine, better go to recovery mode and try resizing it, as recovery mode ensures for OS security and excludes the risk of data loss.

• Restart you Mac and immediately press and hold Option and R keys (or Command key) after you hear startup tone.
• Release the key(s), select Recover HD from the boot manager screen, and click the arrow pointing downwards.
• Select Disk Utility in the main menu and click Continue button.
• Select the hard drive and simultaneously go to the Partition tab in the opened window.
• In the graphical representation of the hard drive, select the Macintosh HD and drag it upward from its bottom right corner to reduce its size.
• Click Apply to save the changes and restart Mac.

Data is the most valuable thing stored on a hard drive; it is suggested to back it up before such modifications.

Creating several partitions of a Mac drive ensures that you can use them to store data categorically so that accessing them will be easier for you. Each partition acts like a separate drive and can be used to install another operating system, if required. In the long run, you create and gather lots of data. However, at any point of time you may feel for the need of repartitioning the hard drive to further save the data more categorically; to create new space for new kind of data; or to create new partition for another OS installation. This; demands for a careful hard drive repartition without data loss.
Though partitioning a Mac hard drive is not a difficult task to perform, you need to be careful and attentive while dealing with it.

Proceeding to Partitioning Safely
Before we focus on how to repartition a Mac drive while the data stored on it remains intact, make sure you have backed up everything that is important. Though the process we are going to follow is secure, backing up the data before repartitioning proves to be a rescue in the event of unwanted data loss.

• Close all the running applications, windows and launch Disk Utility (Go-> Application-> Utility folder-> Disk Utility)
• Select the hard drive you need to repartition from the left-pane (Recognize the drive carefully from the manufacturer’s name, model no., and size, if multiple hard drives are installed).
• Now, click Partition tab in the right-pane and observe the hard drive structure (The data stored on the drive is displayed by blue color while free space by white color).
• Resize* any of the existing Mac partitions by clicking and dragging it from its bottom-right corner (Drag up to increase its size while down to reduce).
• After you create enough free space (displayed at the bottom end), click plus (+) sign below this structure to add a new partition. Set a Name, Format**, and Size for this new partition from the Volume Information area.
• Click Option button below to choose a Partition Map Scheme for this partition. It is recommended to choose GUID Partition Table to make it resizable on an Intel-based Mac. Click OK.
• Click Apply button to save the changes.

*You can resize a Mac volume up to the data stored on it, but only if it is formatted with a Partition Map Scheme as GUID Partition Table.
** Choose a format i.e. Mac OS Extended (Journaled) if you want to use it with Mac Time Machine or as a boot volume. Select Mac OS Extended (No Journaling) if it is for Mac media or for data storage.
Above discussed are the steps for a hard drive to repartition without data loss using Disk Utility; however, several other professional tools in similar category are also available. You need to choose one carefully.

The ‘Disk Utility’ offers various useful features to Mac users and one of these is the support for adding, deleting, resizing, and formatting partitions. Partitions are basically logical divisions of your hard drive that enable you to segregate your data according to its usage. For example by dividing your hard drive into three partitions, you can keep your system files on one, and other useful files on another partition. In this way, with the help of partitions, you can safeguard your data from getting lost when the system files get corrupt and you have to format your hard drive.

Moreover, the Mac OS X 10.5 and later versions have come up with some noticeable changes in ‘Disk Utility’ especially when you are talking about adding, deleting, and resizing volumes or partitions. Though these options are error free and do not cause data losses, but you must know their limitations for safe working. You can create multiple partitions on your hard drive or add a new partition with ‘Disk Utility’, as well as trim the size of an existing partition without encountering data loss, but you have to be careful while increasing the size of a partition.

The first and the foremost limitation of ‘Disk Utility’ for resizing a partition is, it cannot resize Master Boot Record partition. Since Master Boot Record is the first sector of a partitioned hard drive volume, therefore it contains all the information about a disk. Resizing this partition may cause data loss and hence it is prohibited.

Another limitation while resizing is: you can decrease the size of any partition, but to increase its size you should check whether there is enough free space available between the volume you want to expand and the next partition on your hard drive or not. If there is no enough space available below the volume you want to expand, then you have to delete the partition next to it. That means you have to bear data loss of the deleted volume. However, you can easily overcome the loss, if you have backup of the deleted volume.

Therefore, in above mentioned two cases the ‘Disk Utility’ fails to provide smooth and secure method of recovery. For such cases use of a professional partition Mac drive software is recommended. Reliable professional tools of this category resize Mac volumes without any constraints and without causing data loss. Generally efficient utility of this category provides the option to create bootable DVD of your Mac and thus enables you to perform partitioning operations on your boot drive as well. The hide and reveal option in some tools lets you hide any critical partition so that it cannot be accessed by any unauthorized users and reveal it anytime when you want.

Mac OS X has a built-in tool called Disk Utility that facilitates creating, managing, and deleting all your Mac volumes whenever required. It allows you to resize an existing Mac volume, if you need some free memory to create a new volume or to extend an existing one. When you attach a USB drive to your Mac, it detects it on the fly and displays it with all other Mac volumes. Disk Utility facilitates you to partition this external hard drive, just as you create and manage the volumes on your Mac hard drive. Take an example of the scenario, suppose:

You bought 1TB external hard drive to back up your data, and then you think of partitioning it into different volumes and allocating these volumes to store different types of data. As a separate volume behaves like a separate disk, you can install another OS in any of these volumes. However, make sure that the drive does not contain any sort of data before you proceed to partition, as it is first going to format the drive. Let us take a tour of the process to partition external drive.

• Attach your USB hard drive to your Mac and let it be detected on the fly.
• Launch Disk Utility (found in Applications-> Utilities folder).
• Select this external hard drive (it should appear with the name of the manufacturer, if you did not change it) in the left-pane of the Disk Utility window and click ‘Partition’ tab in the right-pane, respectively.
• Select the number of volumes you want to create from the drop-down list under ‘Volume Scheme’ label. For example, if you want to create two partitions, select ‘2 partitions’.
• Select a volume* in the hard drive orientation shown beneath the drop-down list and edit its name, select Format** from the drop-down list, and size under ‘Volume Information’ label.
• Do not Click Apply yet.

*Selecting a volume surrounds its structure with a blue-colored border and its relative details (i.e. ‘Name’, ‘Format’, and ‘Size’) appear to be edited.
**(Select Mac OS Extended (Journaled) if you want to use it with Mac Time Machine or as a boot volume, or Select Mac OS Extended (No Journaling) if it is to be used with Mac media or for data storage.)

You may think that every detail is filled or chosen and click Apply; however, things are yet to be done. Before you click ‘Apply’ button, click ‘Options’ button beneath the disk orientation. It opens a new window showing the partition scheme used for the selected volume. It chooses Master Boot Record (MBR) as a default partition scheme that is a DOS-style scheme. Select GUID Partition Table as it enables you to resize this volume, whenever required. However, if you do not change it or one of the other partition maps i.e. Apple Partition Map (APM) or Master Boot Record (MBR) is selected, you cannot resize it until you delete and rebuild it.

Partitioning a hard drive into several volumes of similar or different sizes during operating system installation, is not a difficult task to perform. However, you do not need to worry if you did not partition your hard drive into slew volumes, as Mac OS X allows you to create a new partition and delete or resize Mac volume through a built-in disk management tool called Disk Utility, whenever required. You can find it in Applications-> Utilities-> Disk Utility.

Risks when modifying a volume
Disk Utility is one of the best tools embedded in Mac OS X that facilitates end user to perform several system-related tasks easily. However, there are several risk factors, which you need to be careful about while performing any of the above mentioned operations on your Mac volumes. A few known possible vulnerabilities are discussed below:

Volume Inaccessibility due to Volume Header Corruption
Every Mac volume has a header (1KB in size) associated with it that stores overall information about its respective volume. This header works as an entry in the Apple Partition Map indexing. In any case, if this volume header of a particular volume gets corrupt, then the respective volume as well as the data stored in it becomes inaccessible, as Mac is not able to detect that volume.

File System Corruption
Mac OS X employs an intelligent file system (HFS, HFSX, HFS+, and HFS wrapper) to format its volumes. Several internal and external factors (such as software and hardware, forced shutdown, power failure etc.) affect these file systems. Modifying a Mac volume is also among the factors affecting these file systems that may cause corruption.

Partition Map Scheme
When you open Disk Utility and select hard drive in the left-pane, it displays certain information in the bottom-pane. Partition Map Scheme is one such information that displays the partition scheme employed to partition that hard drive. You can modify a volume only if it displays GUID Partition Table (GPT). However, you cannot modify a volume if it is formatted with Apple Partition Map (APM) or Master Boot Record (MBR). If you try to do it, it may also affect the logical structure of the respective volume.

Risk while Modifying Boot Volume of Mac
If you try to modify the boot volume of your Mac while being booted from the same, you may suffer from a crash, which may cause complete inaccessibility. Therefore, you need your Mac OS X installation disc if you wish to modify your boot volume.

You need to insert the disc and restart your Mac. Press and hold “Option” and “R” keys during startup to boot in Recovery mode. Go to Disk Utility after it starts up and select “Partition” tab in the right-pane. Click boot volume and drag it through its border to modify it. In case, if you are going to shrink it, you can utilize the unallocated space to create a new volume or enlarge any existing one.

It is always recommended to keep a backup of your data to avoid any sort of risk leading to data inaccessibility or corruption.

Mac OS X facilitates its users to partition their hard drive into several volumes in order to store different types of data separately. In spite of storing different types of data in separate volumes, these volumes can be utilized, in case a user wishes to install another OS on any of these volumes. Generally, users create these hard drive volumes while installing the operating system, but Mac allows creating volumes even after the OS installation using Disk Utility.

Disk Utility is a three-pane window that displays all of the hard drives and their respective volume in the left pane. Click a hard drive in the left-pane and go to the Partitions tab in the right-pane in order to see the orientation of the hard drive. This orientation describes the manner in which it is divided in several volumes. In addition, you can resize a particular volume by dragging it from its border. However, resizing an existing Mac volume requires the user to know the factors on which the operation relies. When a user clicks a particular volume, the bottom-pane displays its properties. Partition Map Scheme is one of these properties that make it clear to the users whether it can be resized or not. For a volume to be resizable, it must be GUID Partition Table (GPT). However, if it displays Master Boot Record (MBR) or Apple Partition Map (APM), that evidently says it cannot be resized.

Risks in Resizing the Boot Volume

If we talk about resizing the boot volume of the Mac, Disk Utility allows you to resize it only if the Partition Map Scheme is GUID Partition Table (GPT). However, resizing boot volume involves risk, as it may cause it to crash and result in data loss.

Precautions to be taken

Resizing a boot volume on a Mac may not be in favor of the user, as it may crash. Therefore, if a user needs to resize boot volume, it requires the Mac to run in Recovery Mode and follow up a few general steps.

• Restart the Mac.
• Press and hold “Option” and “R” keys while booting.
• Open Disk Utility.
• Select the hard drive in the left-pane.
• Go to the Partition tab in the right-pane.
• Click the boot volume of your Mac hard drive in the structure shown.
• Click the border of the volume and drag to resize it.

Click the + button below this resizing window to create a new volume to utilize this free space and click Apply.

Now, restart the Mac and remove the disc and boot in normal mode to see the changes done.

If the volumes are created using GPT, user can resize every individual volume; however, boot volume requires much care while performing such action.