How to get 16k block size in 2.6.38.8 kernel (CentOS x86 64) ?

thamsivan · 12-14-2011, 11:21 AM

Hi All,

I want to know how to get 16k Block size while creating XFS on 2.6.38.8 Kernel
(CentOS)

I realised that one would require 16k pagesize and for that i need to recompile the kernel.
But I'm using x86_64 arch. CPU

So, is there a way around ?
Is there a way to set 16k page size in x8664 and inturn set 16k block size

Note:
I'm creating file system on SSD

-----------------------
Commands that I tried-

Code:

[root@test]# mkfs.xfs -b size=16k /dev/dm-3
meta-data=/dev/dm-3              isize=256    agcount=4, agsize=4341756 blks
         =                       sectsz=512   attr=2
data     =                       bsize=16384  blocks=17367023, imaxpct=25
         =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=16384  ascii-ci=0
log      =internal log           bsize=16384  blocks=8479, version=2
         =                       sectsz=512   sunit=0 blks, lazy-count=1
realtime =none                   extsz=16384  blocks=0, rtextents=0
[root@test]# mount /dev/dm-3 /mnt/dm-disk/ -o sunit=128,swidth=256
mount: Function not implemented

tail var log messg

Code:

Dec 15 04:15:20 test kernel: XFS: SB validate failed
Dec 15 04:15:20 test kernel: XFS: file system with blocksize 16384 bytes
Dec 15 04:15:20 test kernel: XFS: only pagesize (4096) or less will currently work.

johnsfine · 12-14-2011, 02:01 PM

I see the error message you quoted, and its meaning does appear to be clear:

Code:

XFS: only pagesize (4096) or less will currently work.

But ..

Quote:

Originally Posted by thamsivan

I realised that one would require 16k pagesize and for that i need to recompile the kernel.
But I'm using x86_64 arch. CPU

So, is there a way around ?
Is there a way to set 16k page size in x8664

No. 16KB page size is not supported by x86-64 hardware.

x86-64 hardware supports 2048KB pagesize, but I'm pretty sure you don't want that, and I'd be surprised if the Linux kernel has a build-time option to support that if you do want it.

No page size between 4KB and 2048KB is supported.

thamsivan · 12-15-2011, 07:56 AM

Thanks for the reply johnsfine.

I safely assume that 16k page size is not supported in x86_64.

Now,
a. Does it in anyway prevent me from having 16k block size on XFS filesystem ?
b. Would it help me resolve the issue if I use a IA64 server?
c. Is 16k block size on XFS supported in Linux at all ??

johnsfine · 12-15-2011, 08:17 AM

I have no idea about block size in XFS. The error message you quoted is more information than I ever knew on that topic. I was only commenting on page size in x86-64.

Hopefully someone who knows about XFS will reply.