JP Vossen on 12 Jun 2013 14:40:06 -0700

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[PLUG] XFS on CentOS-5.9

Short version: what, if anything, is going to bit me for using a 26TB XFS filesystem on CentOS-5.9?


I recently had a problem trying to format a partition larger than 16TB on CentOS-5.9 on a Dell PE720 with 8x4TB drives in a PERC H710 hardware RAID5. Neither ext3 nor ext4 would work, even though in theory, and possibly with newer 'e4fsprogs', ext4 should work (after 'yum install e4fsprogs' since that's not in the stock install). I had a multitude of problems, all of which boiled down to:
	1) CentOS-5.9 is *old*
	2) 32-bits is not enough

I am running x86_64, but with CentOS-5 at least, there are still far too many i386 tools and libs installed and I was hitting:
	mked4fs 1.41.12 (17-May-2010)
mkfs.ext4: size of device /dev/sdb1 too big to be expressed in 32 bits using a blocksize of 4096

Interestingly, I was hitting that at 17.6TB, *not* the "16TB limit" that everyone else talks about (yes, I know the meaning of "TB" is fuzzy . As far as I can tell, using 8k block sizes on i386 or x86_64 is not allowed, attempts to remove the 32-bit libs failed for dependencies, and "-O 64bit" also failed as above. mkfs.ext4 -O 64bit,has_journal,extent,huge_file,flex_bg,uninit_bg,dir_nlink,extra_isize -m2 -L /data /dev/sdb1

On the other hand, XFS was backported into the CentOS stock repos, and that Just Worked, so far at least:
	yum install xfsprogs
	parted -s /dev/sdb mklabel gpt
	parted -s -- /dev/sdb mkpart primary xfs 0 -1
	  # -s = script mode, no prompts
	  # -- = end of options, rest are arguments
	  # Start at 0 and end at '-1' = whole disk, no matter what size
	mkfs.xfs -fL /data /dev/sdb1
	  # -f  = Force
	  # -L  = Set new volume label

That worked and was *far* faster, seconds to format 26TB as opposed to 20-30 minutes for ext4 to format 17.6TB on pretty fast hardware.

So...what, if anything, is going to bit me for using this?

JP Vossen, CISSP            |:::======|
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