What is the maximum supported XFS block size in RHEL?

Solution Verified - Updated -

Issue

  • According to man mkfs.xfs, it says that block size can be specified up to 65536:

    $ man mkfs.xfs
    :
    -b block_size_options
           This option specifies the fundamental block size of the filesys‐
           tem.   The valid block_size_options are: log=value or size=value
           and only one can be  supplied.   The  block  size  is  specified
           either as a base two logarithm value with log=, or in bytes with
           size=.  The default value is 4096 bytes (4 KiB), the minimum  is
           512,  and the maximum is 65536 (64 KiB).  XFS on Linux currently
           only supports pagesize or smaller blocks.
    :
    
  • We confirmed that it could be specified up to 65536 (see below). However, it also says XFS on Linux currently only supports pagesize or smaller blocks:

    # mkfs -t xfs -f -s size=4096 -b size=16384 /dev/sdb1
    meta-data=/dev/sdb1              isize=256    agcount=4, agsize=16368 blks
           =                       sectsz=4096  attr=2, projid32bit=1
           =                       crc=0        finobt=0
    data     =                       bsize=16384  blocks=65472, imaxpct=25
           =                       sunit=0      swidth=0 blks
    naming   =version 2              bsize=16384  ascii-ci=0 ftype=0
    log      =internal log           bsize=16384  blocks=512, version=2
           =                       sectsz=4096  sunit=1 blks, lazy-count=1
    realtime =none                   extsz=16384  blocks=0, rtextents=0
    
    mkfs -t xfs -f -s size=4096 -b size=32768 /dev/sdb1
    meta-data=/dev/sdb1              isize=256    agcount=4, agsize=8184 blks
           =                       sectsz=4096  attr=2, projid32bit=1
           =                       crc=0        finobt=0
    data     =                       bsize=32768  blocks=32736, imaxpct=25
           =                       sunit=0      swidth=0 blks
    naming   =version 2              bsize=32768  ascii-ci=0 ftype=0
    log      =internal log           bsize=32768  blocks=512, version=2
           =                       sectsz=4096  sunit=1 blks, lazy-count=1
    realtime =none                   extsz=32768  blocks=0, rtextents=0
    
    # mkfs -t xfs -f -s size=4096 -b size=65536 /dev/sdb1
    meta-data=/dev/sdb1              isize=256    agcount=4, agsize=4092 blks
           =                       sectsz=4096  attr=2, projid32bit=1
           =                       crc=0        finobt=0
    data     =                       bsize=65536  blocks=16368, imaxpct=25
           =                       sunit=0      swidth=0 blks
    naming   =version 2              bsize=65536  ascii-ci=0 ftype=0
    log      =internal log           bsize=65536  blocks=512, version=2
           =                       sectsz=4096  sunit=1 blks, lazy-count=1
    realtime =none                   extsz=65536  blocks=0, rtextents=0
    
    # mkfs -t xfs -f -s size=4096 -b size=131072 /dev/sdb1
    illegal block size 131072
    Usage: mkfs.xfs
    :
    
  • Does it mean as it shows Red Hat also does not support XFS if block size exceeds pagesize even though it can be specified beyond pagesize?

  • What is the maximum pagesize supported by XFS?

Environment

  • Red Hat Enterprise Linux (RHEL) 6, 7
  • xfsprogs

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