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Re: Default mount options (that suck less).

To: xfs@xxxxxxxxxxx
Subject: Re: Default mount options (that suck less).
From: Niv Sardi <xaiki@xxxxxxx>
Date: Thu, 1 Nov 2007 10:35:16 +1100
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Thanks for all your insightfull replys

Here's the state of my xfsprogs/TODO:

DONE - version 2 logs
DONE - attr2

BUG - lazy superblock counters

It looks like it's a fixed bug that should be commited soon:

>[itchy] dmesg -c
>[itchy] dd if=/dev/zero of=blah bs=1 seek=100G count=1
1+0 records in
1+0 records out
1 byte (1 B) copied, 0.00151443 s, 0.7 kB/s
# this is my patched mkfs
>[itchy] mkfs.xfs -f -l lazy-count=1 blah
meta-data=/home/xaiki/blah       isize=256    agcount=8, agsize=3276800 blks
         =                       sectsz=512   attr=2
data     =                       bsize=4096   blocks=26214400, imaxpct=25
         =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096  
log      =internal log           bsize=4096   blocks=12800, version=2
         =                       sectsz=512   sunit=0 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0
>[itchy] mount -o loop blah /mnt
mount: wrong fs type, bad option, bad superblock on /dev/loop0,
       missing codepage or helper program, or other error
       In some cases useful info is found in syslog - try
       dmesg | tail  or so

>[itchy] dmesg -c
XFS: bad version
XFS: SB validate failed

DONE - version 2 inodes

DONE - dropping the ability to turn unwritten extents off completely

DONE/ASK - imaxpct default can be reduced

> Given that 25% on a 4GB filesystem will allow about 5million inodes,
> I think it's probably reasonable to bring it down to 5% by the time we
> pass 1TB and 1% by 50TB.....

I implemented this as a simple step function, do we need something smarter ?

ASK - larger log

> Another one for you - make the log larger. The kernel code supports
> a log of up to 2GB, so mkfs could making a larger log without
> requiring changes elsewhere.

dchiner told me that we have issues with big logs, anyway, how much shall 
I increase the default ?

ASK - less allocation groups for single disk configs

Again, being quite new, I'd need magnitude orders of what's reasonable, I now 
multiply
by 2 the AG size, witch gives me 2x less AGs.

Eric: mkfs.conf sounds like a great idea to me, but i don't think it should
be exclusive to XFS.

Please find attached the early patches, comments are welcome.

Cheers,
-- 
Niv

Attachment: 0001-Default-to-log-version-2.patch
Description: Text document

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