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question: are the metadata crc elements ready for general use?

DISCUSSION Joe Landman 2 participants 2 messages Apr 28, 2015

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Joe Landman

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I ask as I see this in the 3.2.2 mkfs.xfs command. The default is to leave them off from what I can see on an mkfs.xfs.

root@unison:~/xfsprogs# mkfs.xfs /dev/sda
meta-data=/dev/sda               isize=256    agcount=55, agsize=268435455 blks
         =                       sectsz=512   attr=2, projid32bit=1
         =                       crc=0        finobt=0
data     =                       bsize=4096   blocks=14627632640, imaxpct=1
         =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096   ascii-ci=0 ftype=0
log      =internal log           bsize=4096   blocks=521728, version=2
         =                       sectsz=512   sunit=0 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0

But they are there, and I am curious as to the developers/users thoughts. Will they break things (nfs, CIFS/samba)?

Thanks!

Joe

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#1 lore raw
Quoted 2 lines · Joe Landman

I ask as I see this in the 3.2.2 mkfs.xfs command. The default is to leave them off from what I can see on an mkfs.xfs.

Yes, and we've been discussing whether they should be made the default in the upcoming 3.2.3 release or wait for 3.3. IIRC, the latest SLES release already defaults to using CRCs by default.

Quoted 12 lines
root@unison:~/xfsprogs# mkfs.xfs /dev/sda
meta-data=/dev/sda               isize=256    agcount=55,
agsize=268435455 blks
         =                       sectsz=512   attr=2, projid32bit=1
         =                       crc=0        finobt=0
data     =                       bsize=4096   blocks=14627632640, imaxpct=1
         =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096   ascii-ci=0 ftype=0
log      =internal log           bsize=4096   blocks=521728, version=2
         =                       sectsz=512   sunit=0 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0
Quoted 2 lines

But they are there, and I am curious as to the developers/users thoughts. Will they break things (nfs, CIFS/samba)?

I enable them on all my systems, and almost all of my testing is done with "-m crc=1,finobt=1" options set. The don't affect applications at all - CRCs are completely transparent to userspace so applications don't even know the filesystem is using them.

Cheers,

Dave.

Signature · 7 lines
Dave Chinner
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