Is Linux Ready for 4096 Byte Sector Hard Drives?

Posted 02/15/2010 at 11:40am | by Paul Lilly

4

Comments

Print

On paper, Linux doesn't seem susceptible to any of the performance pitfalls associated with transitioning from 512-byte to 4096-byte sector hard drives, but is that really the case? According to Timothy Miller, founder of the Open Graphics Project, Linux is just as vulnerable to the potential performance impact as Windows XP.

Miller came to his conclusion after picking up a pair of new Western Digital Caviar Green drives and putting the paper assumption to the test.

"The problem most likely to hit you with one of these drives is very slow write performance," Miller wrote on his blog. "This is caused by improper logical-to-physical sector alignment. OS's like Linux use 4K blocks (or multiples of 4K) to store data, which matches well with the physical sector. However, nothing restricts you from creating a partition that starts on an odd-numbered 512-byte logical sector. This misalignment causes a performance hit since the drive has to read and rewrite the 4K sectors with whatever 512-byte slices changed."

Miller's findings fly in the face of WD's claims, who says that both Mac OS X and Linux would be "unaffected." During Miller's testing, he found that 1000 random aligned 4K writes consistently took between 7 and 8 seconds, while the same number of unaligned 4K writes took between 22 and 24 seconds, or three times longer.

"We've known about this issue for LONG time, and now it's here, and we haven't fully prepared," Miller added.

Get the full scoop here.