External hard drive

[v2club]

I have transfered some of my stuff on a 1TB external hd from a PC, if HYPOTHETICALLY any of the contained files is infected with malware is that gonna harm my Mac? And since I'm on the topic, the mentioned 1TB external HD is NTFS formated by default, how do I use it with the Time Machine? Do I have to format it to FAT32 or exFAT format?

 

[simsaladimbamba]

Windows malware can't harm Mac OS X, as it can't be executed, just like you can't run a Windows application in Mac OS X natively.

Mac Virus/Malware Info by GGJstudios
There are currently no viruses for Mac OS X in public circulation, only a handful of trojans and other malware, which have to be installed manually via entering the administrator password.
The only anti-virus you need to protect your Mac is education and common sense.​

As to NTFS and Time Machine: it will not work, as TM needs HFS+ as format.

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

Maybe you divide the HDD into two volumes, one containing the TM backup and the other for data.

 

[karohan]

If there are any viruses from your PC on your external, they cannot infect your Mac because PC viruses cannot infect a Mac. However, if you transfer those files to another PC, they can infect those PCs. Furthermore, if you have a trojan for Macs on your external, transfer it to your Mac, and install/open it, you can infect your Mac (though this is unlikely).

Secondly, you cannot use NTFS with Time Machine. Not to mention, I don't think exFAT or FAT32 works either. It needs to be formatted to HFS+, I think. You can just open Time Machine, and you can automatically set it up there.

EDIT: Haha, someone posted right before I did, and said everything far better than I did.