HP Ext. HD says read only, fix possible?

[wordsmith27]

I have an hp external hard drive that I used to backup my win 7 laptop but I left a lot of space and want to backup my mac problem is it says read only...is there a way to make it writable?

 

[simsaladimbamba]

It is probably using NTFS as file system, to check:

Finder > select external HDD >> GET INFO >>> Format and Sharing & Permissions

FAT32 (File Allocation Table)

• Read/Write FAT32 from both native Windows and native Mac OS X.
• Maximum file size: 4GB.
• Maximum volume size: 2TB

NTFS (Windows NT File System)

• Read/Write NTFS from native Windows.
• Read only NTFS from native Mac OS X
  [*]To Read/Write/Format NTFS from Mac OS X: Install NTFS-3G for Mac OS X (free)
  
• Some have reported problems using Tuxera (approx 33USD).
• Native NTFS support can be enabled in Snow Leopard, but is not advisable, due to instability.
• AirPort Extreme (802.11n) and Time Capsule do not support NTFS
• Maximum file size: 16 TB
• Maximum volume size: 256TB

HFS+ (Hierarchical File System, a.k.a. Mac OS Extended)

• Read/Write HFS+ from native Mac OS X
• Required for Time Machine or Carbon Copy Cloner backups of Mac internal hard drive.
• To Read/Write HFS+ from Windows, Install MacDrive
• To Read HFS+ (but not Write) from Windows, Install HFSExplorer
• Maximum file size: 8EiB
• Maximum volume size: 8EiB

exFAT (FAT64)

• Supported in Mac OS X only in 10.6.5 or later.
• Not all Windows versions support exFAT. See disadvantages.
• exFAT (Extended File Allocation Table)
• AirPort Extreme (802.11n) and Time Capsule do not support exFAT
• Maximum file size: 16 EiB
• Maximum volume size: 64 ZiB

PS: Time Machine does not work with NTFS formatted HDDs, maybe you can partition it though, but as I don't do it that often (using Windows and external HDDs formatted with NTFS), I don't know about that particular problem.

Maybe have a look at Advanced Search to find similar threads:

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[wordsmith27]

thanks,

so for time machine I need to get an ext. HD that works for mac? I'll look into that as well.

 

[simsaladimbamba]

thanks,

so for time machine I need to get an ext. HD that works for mac? I'll look into that as well.

No need to get a special HDD, as every HDD can be formatted with every available file system. You just need to format it correctly, but as your HDD already is formatted via Windows, you would lose all data during another format, thus you could partition it, but as I never had to partition an NTFS formatted HDD for Time Machine use, I don't know the steps. Maybe the Advanced Search I pointed to or the following FAQ can help.
Time Machine FAQ