Hi I'm trying to resize an ext4 filesystem from 10TB to 25TB. I'm running on a 32bit machine and using latest e2fsprogs-1.42.8 and kernel 3.8. When doing so I'm getting a memory allocation failure: $ > resize2fs -d 255 -f /dev/md1 25T resize2fs 1.42.8 (20-Jun-2013) Resizing the filesystem on /dev/md1 to 6710886400 (4k) blocks. read_bitmaps: Memory used: 160k/373856k (40k/121k), time: 37.14/ 0.44/ 0.23 read_bitmaps: I/O read: 21MB, write: 0MB, rate: 0.57MB/s fix_uninit_block_bitmaps 1: Memory used: 160k/373856k (40k/121k), time: 78.82/78.75/ 0.05 adjust_superblock: Memory used: 160k/2127584k (42k/119k), time: 51.05/50.58/ 0.46 fix_uninit_block_bitmaps 2: Memory used: 160k/2127584k (42k/119k), time: 197.02/196.95/ 0.02 /mnt/e2fsprogs-1.42.8/resize/resize2fs: Memory allocation failed while trying to resize /dev/md1 Please run 'e2fsck -fy /dev/md1' to fix the filesystem after the aborted resize operation. Above shows 2G+ mem allocations. In the failure case the allocations gets close to 3GB, which can't be handle on a 32bit machines. Looking into the resize code I see the big allocations are a result of the bitmap block array allocations. I also found some threads that already reported similar issues. Using BIGALLOC option is much more memory efficient, and I can overcome the resize, but I have my doubts about it: 1. It seems to break compatibility to older existing FS without BIGALLOC. if I will need to move an existing EXT4 disk array to this machine I wouldn't be able to resize it as there is no tune2fs support for BIGALLOC, am I right? 2. There are some warning notes on the ext4 wiki about resize with BIGALLOC which make me wonder if it will be wise to use it... I also noticed that there is an option to use rb-tree instead of block array for managing bitmaps, which seems to be much more memory efficient and still dont break compatibility with existing FS. However I dont see any option to use it for resize, any reason for this? Thanks for your advice. -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
