Large Filesystem Creation
February 11th, 2008 Posted in LinuxThis post will be reasonably short, since there’s not really that much detail to get into. What we’re talking about here is large filesystem support, and the related limitations.
Using the standard MSDOS disk label (the default for nearly every x86( and x86_64) OS out there, you can have a maximum of a 2TB partition. To get larger than that, you need to use GPT. You can do this by using parted. Using fdisk on partitions larger than 2TB will have some fairly nasty side-effects and can eat your data. This is because fdisk has a 2TB limit to the sizes that it can handle. Anything over 2 TB, and it won’t write properly. In addition, with the version of grub shipping in centos and RHEL, you can’t boot to a partition larger than 2TB so you’ll have to use a sane disk layout and create an OS partition to go along with your data partition.
At 8TB and above, you’ll run into the next set of issues. By default, mkfs.ext3 won’t let you create a filesystem larger than 8TB, and will fail with an error along the lines of “Filesystem too large: No more than 2* 31-1 blocks”. This is mostly a lie, as CentOS 5 and RHEL 5 support up to 16TB for ext3. You simply have to pass -F to mkfs.ext3 in order to get it to create the filesystem.