On Jul 02, 2009 15:23 -0700, Justin Maggard wrote: > I've been toying with ext4 and e2fsprogs pu branch (pulled from git > yesterday) on very large volumes, and I've run into some issues. What > I've found so far with an 19TB MD RAID0 volume, running 2.6.29.4 (I'm > planning on trying 2.6.30 soon): > > - mkfs.ext4 *appears* to work fine, reporting no errors. Examining > the superblock info with dumpe2fs -h looks normal -- although I'm > unfamiliar with "Lifetime writes" field, and I'm not sure why it's at > 73GB immediately after doing mkfs, before ever mount it. > > - Immediately running e2fsck on the volume before ever mounting it > will not complete, and results in the following: > # e2fsck -n /dev/md2 > e2fsck 1.41.7 (29-June-2009) > Error reading block 2435874816 (Attempt to read block from filesystem > resulted in short read). Ignore error? no > /dev/md2: Attempt to read block from filesystem resulted in short read > while reading block 2435874816 > /dev/md2: Attempt to read block from filesystem resulted in short read > reading journal superblock > e2fsck: Attempt to read block from filesystem resulted in short read > while checking ext3 journal for /dev/md2 It looks like there may be some problem with the underlying device? I posted a program here a few months ago called "ll_ver_dev" which can quickly (or slowly) verify that writes and reads to different offsets in a block device return consistent data. The quick version will detect such problems as 32-bit overflows, but if you are having strange problems you might need to run the full version. You could also try running with a filesystem just under 16TB and verifying that works. > - Mounting with -o noload does appear to work, and reading and > writing seems to work fine. That's because the journal is not being used, which is what seems to be having the problem. I wonder if the journal is beyond 8TB or beyond 16TB for some reason and this is causing grief? > - Setting default mount options with tune2fs works fine, as expected. > > - Then, I went on to check out filesystem resizing. I created an LVM > 15TB LV, and ran mkfs.ext4 on it. Looking at the superblock info, it > did not contain the 64bit flag, which I assume is expected behavior. > I extended the LV to ~18TB and tried resize2fs, and got this error: > resize2fs: Can't read an block bitmap while trying to resize /dev/data/data0 This is known not to work, AFAIR. Cheers, Andreas -- Andreas Dilger Sr. Staff Engineer, Lustre Group Sun Microsystems of Canada, Inc. -- 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
