2TB and larger harddrives support?

[xerces8]

Hi!

With 2TB and 3TB drives available, how is the support from the Ubuntu side?

Anyone tried?
Developers?

Regards,
David

[akand074]

Ubuntu uses EXT4 file system. EXT4 supports up to 1 Exabyte, with the max size for a single file of 16 Terabytes. I've used a 1TB and 2TB driver personally.

[xerces8]

The problem is with partitioning, not file systems.

I will try it with a virtual machine, when I have time...

[akand074]

The problem is with partitioning, not file systems.

I will try it with a virtual machine, when I have time...

What about partitioning? You're allowed up to 4 primary partitions, and as many logical partitions as you want, just like any other hard drive. You can do it with Ubuntu fine with any working hard drive including 2TB and 3TB drives.

[xerces8]

What if we wait for someone who is aware that the MS-DOS partition format (also known as MBR) can only handle partitions of 2 TB maximum size, shall we?

[cascade9]

What if we wait for someone who is aware that the MS-DOS partition format (also known as MBR) can only handle partitions of 2 TB maximum size, shall we?

What if somebody said 'GPT'? (GUID Partition Table).

http://en.wikipedia.org/wiki/GUID_Partition_Table

2TB sounds big, but the ladies, genetlemen and small furry creatures from Alpha Centauri who have been using RAID found the 2TB limit quite some time ago.....

[ronparent]

That reference was quite informative.

2TB sounds big, but the ladies, genetlemen and small furry creatures from Alpha Centauri who have been using RAID found the 2TB limit quite some time ago.....

... and I love your sense of humor.

[srs5694]

First, the limit on MBR is 2 TiB (2 x 2^40 bytes), not 2 TB (2 x 10^12 bytes). Modern 2 TB drives are enough under the 2 TiB limit that they have no problems with MBR.

Second, the 2 TiB limit applies when the disk uses 512-byte sectors, since disk addressing on this level is normally done using sector pointers; the MBR limit derives from the fact that is uses 32-bit sector pointers, so it's really a limit of 2^32 sectors. Multiply that by 512 (2^9) and you get 2^41 -- or 2 x 2^40, as stated earlier. If the sector size is increased to 4096, as some drives now use, then the limit goes up to 2^32 x 2^12 = 2^44 bytes, or 16 TiB. Note that this applies to logical sector size. Some drives today use 4096-byte physical sector sizes but use 512-byte physical sector sizes, so the 32-bit sector limit works out to 2 TiB for them.

As to the heart of the question, one need only use GPT to bypass this limit; GPT uses 64-bit sector pointers, so the limit becomes 2^64 x 2^9 bytes = 2^73 bytes, or 8 ZiB, when using 512-byte sectors (or 64 ZiB when using 4096-byte sectors). Ubuntu's support for GPT is good, although there are some caveats. Mostly these relate to buggy BIOSes, as described on this page of mine. You should also be aware of some of GPT's capabilities and requirements, as well as the needs of your boot loader when using GPT. In particular, GRUB 2 works best with a BIOS Boot Partition when used with GPT on a BIOS-based computer. If your computer uses EFI rather than BIOS, Ubuntu's support becomes rather weak, but that's a firmware issue, not a partition table issue per se.

Filesystem limits can become an issue. According to Wikipedia, the maximum filesystem size for ext3fs is 16 TB, but I believe it's actually 16 TiB. Ext4fs has a much higher limit (1 EiB), but the current partition creation tools impose a lower 16 TiB limit. If you want to use a really big disk (as in a RAID array or a drive that's fallen through a wormhole from the future), you're better off using XFS (8 EiB maximum filesystem size) or JFS (32 PiB maximum filesystem size) for the moment. Note that filesystem sizes are independent of the disk's sector size, but they do sometimes depend on the allocation block size used in the filesystem itself.

[srs5694]

a

[srs5694]

a