From Bugzilla Helper: User-Agent: Mozilla/5.0 (Windows; U; WinNT4.0; en-US; rv:1.0.2) Gecko/20030208 Netscape/7.02 Description of problem: vgcreate was able to create a volume group of 2.22TB from two 1.11TB raids using: 'vgcreate -s64m VG1 /dev/sdc /dev/sdd'. According to my calculations (64m x 65536 = 4.2TB), I should be able to create a logical volume of up to 4 terabytes using a physical extent of 64m. However, the command: 'lvcreate -L2.22T -nLV1 VG1' yeilds the error: lvcreate -- rounding size up to physical extent boundary lvcreate -- size 2383675392 KB is larger than maximum VGDA kernel size of 2147483647 KB Backing off to just 2 terabytes worked ala the following: 'lvcreate -L2T -nLV1 VG1' lvcreate -- doing automatic backup of "VG1" lvcreate -- logical volume "/dev/VG1/LV1" successfully created Version-Release number of selected component (if applicable): lvm-1.0.3-12, kernel version 2.4.20-18.9smp How reproducible: Always Steps to Reproduce: 1. steps to reproduce stated in above description 2. 3. Additional info:
The Linux block device layer is limited to 2TB in the 2.4 kernel. This is not a bug, simply an upper limit that all block devices share, be they physical or logical.
Thank you very much for the quick response. However, I suppose I should have added to my initial post: "If this is not a bug, then when will RedHat Linux support logical voumes greater than 2 terabytes?" This is critical as we are migrating from older legacy systems that DO support >2TB filesystems and RedHat's documentation on LVM implies that >2TB logical filesystems are possible (since >2TB volume groups are clearly possible). So, at the very least, I'm re-opening this to point out a bug in the documentation. The docs need to indicate that there is a 2TB limit. We very much need to know if/when the greater capacity will be supported. Thank you
Individual block devices larger than 2TB will not be supported until the 2.6 kernel is ready for production use. If you could let me know just which documentation you would like this limit mentioned in, I'll pass that request on.
> Individual block devices larger than 2TB will not be supported until the 2.6 > kernel is ready for production use. Thank you! This is most helpful for planning purposes. > If you could let me know just which documentation you would like this limit > mentioned in, I'll pass that request on. Certainly, and thank you! I would think at the very least, a mention of the 2TB limit could be placed early on in the lvm man page. A good place looks to be right after the last sentence of the first paragraph, where it mentions the size of a logical volume is in multiples of physical extents. Also in vgcreate and lvcreate man pages. Those 3 man pages, at least, will have been read in all likelihood by anyone attempting to create logical volumes. It could be as simple as "Note: the current linux kernel, through 2.5, does not support logical volumes past 2 terabytes." Or something like that. Again, many thanks
This is documented in lvm.8