[CentOS] XFS : Taking the plunge

Hi All,

I have been trying out XFS given it is going to be the file system of 
choice from upstream in el7. Starting with an Adaptec ASR71605 populated 
with sixteen 4TB WD enterprise hard drives. The version of OS is 6.4 
x86_64 and has 64G of RAM.

This next part was not well researched as I had a colleague bothering me 
late on Xmas Eve that he needed 14 TB immediately to move data to from an 
HPC cluster. I built an XFS file system straight onto the (raid 6) logical 
device made up of all sixteen drives with.


> mkfs.xfs -d su=512k,sw=14 /dev/sda


where "512k" is the Stripe-unit size of the single logical device built on 
the raid controller. "14" is from the total number of drives minus two 
(raid 6 redundancy).

Any comments on the above from XFS users would be helpful!

I mounted the filesystem with the default options assuming they would be 
sensible but I now believe I should have specified the "inode64" mount 
option to avoid all the inodes will being stuck in the first TB.

The filesystem however is at 87% and does not seem to have had any 
issues/problems.

> df -h | grep raid
/dev/sda               51T   45T  6.7T  87% /raidstor

Another question is could I now safely remount with the "inode64" option 
or will this cause problems in the future? I read this below in the XFS 
FAQ but wondered if it have been fixed (backported?) into el6.4?

""Starting from kernel 2.6.35, you can try and then switch back. Older 
kernels have a bug leading to strange problems if you mount without 
inode64 again. For example, you can't access files & dirs that have been 
created with an inode >32bit anymore.""

I also noted that "xfs_check" ran out of memory and so after some reading 
noted that it is reccommended to use "xfs_repair -n -vv" instead as it 
uses far less memory. One remark is so why is "xfs_check" there at all?

I do have the option of moving the data elsewhere and rebuilding but this 
would cause some problems. Any advice much appreciated.

Steve