What to do if your external hard drive is read-only in Mac

I have been using a 250GB Seagate external hard-drive for quite some time without any issues on Windows XP.

Recently, while migrating to Mac OS X, I realized that I was unable to write to my disk from Mac at all. It all worked fine on Windows XP.

After some bit of digging around, I found out the file system incompatibilities across these OSes. Following is the information of interest:

File System	Windows		Mac OS X
File System	Read	Write	Read	Write
FAT32	Yes	Yes	Yes	Yes
NTFS	Yes	Yes	Yes	No
HFS+	No	No	Yes	Yes

By default, the new external hard-drives are pre-formatted in NFTS filesystem format. This works like a charm on Windows but becomes non-writable in Mac as NTFS is not supported on it . FAT32, however, is compatible across these OSes.

I could not find out any way to convert the NTFS drive to FAT32 without loosing data (I remember that Partition Magic used to do that but could not get that software anywhere).

After a little more digging, I found out about NTFS-3G, an open source cross-platform implementation of the NTFS file system with read-write support. NTFS-3G uses the FUSE, so it can run unmodified on many different OSes.

The latest version is available for download here. After installing this, I can now read & write to my external hard-drive from Mac OS X.

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Published:: 2.16.10 / 7pm

Category:: Mac

Tags:: external hard-drive, filesystem, mac applications, mac os x, migration

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I have over 6 years of experience in architecting and developing web applications.

I am currently working at Akamai Technologies as a Sr. Software Engineer responsible for gathering/conceptualizing requirements and architecting the “Media Analytics” product, which is part of the Akamai HD Network. Previously at Akamai, I was working in the portal development team for the “Performance Analytics” suite of products, responsible for feature development and usability enhancements. At Akamai, I have gained an in-depth understanding of the business of online “Analytics”, and building & using large-scale software for it.

Prior to this, I worked as a Technical Architect at Info Edge (I) Ltd (company that owns high traffic portals like: Naukri.com, Jeevansaathi.com, Brijj.com, 99acres.com etc.). I was the first member of the Brijj.com technical team and was responsible for hiring and bootstrapping the complete team; and architecting the product. For Naukri.com, I played a key role in implementing and optimizing Lucene based distributed and scalable Resume Search Engine in Core Java. I was also responsible for performance tweaking (Apache & Lighttpd for high performance and low response time), and taking initiatives to deliver smart, fast and quality products for the company.

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What to do if your external hard drive is read-only in Mac

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