[linux-lvm] lv raid - how to read this?

lejeczek peljasz at yahoo.co.uk
Thu Sep 7 08:06:27 UTC 2017

hi fellas

I'm setting up a lvm raid0, 4 devices, I want raid0 and I 
understand & expect - there will be four stripes, all I care 
of is speed.
I do:
$ lvcreate --type raid0 -i 4 -I 16 -n 0 -l 96%pv 
intel.raid0-0 /dev/sd{c..f} # explicitly four stripes

I see:
$ mkfs.xfs /dev/mapper/intel.sataA-0 -f
meta-data=/dev/mapper/intel.sataA-0 isize=512    agcount=32, 
agsize=30447488 blks
          =                       sectsz=512   attr=2, 
          =                       crc=1        finobt=0, 
data     =                       bsize=4096   
blocks=974319616, imaxpct=5
          =                       sunit=4      swidth=131076 
naming   =version 2              bsize=4096   ascii-ci=0 ftype=1
log      =internal log           bsize=4096   blocks=475744, 
          =                       sectsz=512   sunit=4 blks, 
realtime =none                   extsz=4096   blocks=0, 

What puzzles me is xfs's:
  sunit=4      swidth=131076 blks
and I think - what the hexx?

In a LVM non-raid stripe scenario I've always remember it 
was: swidth = sunit * Y where Y = number of stripes, right?

I'm hoping some expert could shed some light, help me(maybe 
others too) understand what LVM is doing there? I'd appreciate.
many thanks, L.

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