Re: Maximum file system size of XFS?

[Martin Steigerwald <Martin@lichtvoll.de>]

Am Montag, 11. März 2013 schrieb Martin Steigerwald:
> 2) Create a insanely big sparse file
> 
> merkaba:~> truncate -s1E /mnt/zeit/evenmorecrazy.img
> merkaba:~> ls -lh /mnt/zeit/evenmorecrazy.img
> -rw-r--r-- 1 root root 1,0E Mär 11 22:37 /mnt/zeit/evenmorecrazy.img
> 
> (No, this won´t work with Ext4.)

Okay, you can´t go beyond 8 EiB for a single file which is about what I have 
read somewhere:

merkaba:/mnt/zeit> ls -lh
insgesamt 0
-rw-r--r-- 1 root root 1,0E Mär 11 22:37 evenmorecrazy.img
merkaba:/mnt/zeit> truncate -s2E /mnt/zeit/evenmorecrazy.img
merkaba:/mnt/zeit> truncate -s3E /mnt/zeit/evenmorecrazy.img
merkaba:/mnt/zeit> truncate -s4E /mnt/zeit/evenmorecrazy.img
merkaba:/mnt/zeit> truncate -s5E /mnt/zeit/evenmorecrazy.img
merkaba:/mnt/zeit> truncate -s6E /mnt/zeit/evenmorecrazy.img
merkaba:/mnt/zeit> truncate -s7E /mnt/zeit/evenmorecrazy.img
merkaba:/mnt/zeit> LANG=C truncate -s8E /mnt/zeit/evenmorecrazy.img
truncate: invalid number '8E': Value too large for defined data type
merkaba:/mnt/zeit#1> ls -lh  
insgesamt 0
-rw-r--r-- 1 root root 7,0E Mär 11 22:49 evenmorecrazy.img

So so tests stops there, until you concatenate two of those files with LVM 
or SoftRAID 0 (if that works). Like this (I just had to try it):


merkaba:/mnt/zeit> ls -lh                                           
insgesamt 0
-rw-r--r-- 1 root root 7,0E Mär 11 22:49 evenmorecrazy.img
-rw-r--r-- 1 root root 7,0E Mär 11 22:52 evenmorecrazy.img2
merkaba:/mnt/zeit> losetup /dev/loop0 evenmorecrazy.img
merkaba:/mnt/zeit> losetup /dev/loop1 evenmorecrazy.img2

merkaba:/mnt/zeit#5> pvcreate /dev/loop0       
  Physical volume "/dev/loop0" successfully created
merkaba:/mnt/zeit> pvcreate /dev/loop1
  Physical volume "/dev/loop1" successfully created
merkaba:/mnt/zeit> vgcreate justinsane /dev/loop0 /dev/loop1
  PV /dev/loop0 too large for extent size 4,00 MiB.
  Format-specific setup of physical volume '/dev/loop0' failed.
  Unable to add physical volume '/dev/loop0' to volume group 'justinsane'.


merkaba:/mnt/zeit#5> vgcreate --physicalextentsize 16M  justinsane 
/dev/loop0 /dev/loop1
  PV /dev/loop0 too large for extent size 16,00 MiB.
  Format-specific setup of physical volume '/dev/loop0' failed.
  Unable to add physical volume '/dev/loop0' to volume group 'justinsane'.

merkaba:/mnt/zeit#5> vgcreate --physicalextentsize 128M  justinsane 
/dev/loop0 /dev/loop1
  PV /dev/loop0 too large for extent size 128,00 MiB.
  Format-specific setup of physical volume '/dev/loop0' failed.
  Unable to add physical volume '/dev/loop0' to volume group 'justinsane'.

merkaba:/mnt/zeit#5> vgcreate --physicalextentsize 1G  justinsane /dev/loop0 
/dev/loop1
  PV /dev/loop0 too large for extent size 1,00 GiB.
  Format-specific setup of physical volume '/dev/loop0' failed.
  Unable to add physical volume '/dev/loop0' to volume group 'justinsane'.

merkaba:/mnt/zeit#5> vgcreate --physicalextentsize 4G  justinsane /dev/loop0 
/dev/loop1
  Volume group "justinsane" successfully created

merkaba:/mnt/zeit> vgs                                                               
  VG         #PV #LV #SN Attr   VSize   VFree 
  justinsane   2   0   0 wz--n-  14,00e 14,00e
  merkaba      1   4   0 wz--n- 278,99g  4,85g
merkaba:/mnt/zeit>

merkaba:/mnt/zeit> vgdisplay justinsane
  --- Volume group ---
  VG Name               justinsane
  System ID             
  Format                lvm2
  Metadata Areas        2
  Metadata Sequence No  1
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                0
  Open LV               0
  Max PV                0
  Cur PV                2
  Act PV                2
  VG Size               14,00 EiB
  PE Size               4,00 GiB
  Total PE              3758096382
  Alloc PE / Size       0 / 0   
  Free  PE / Size       3758096382 / 14,00 EiB
  VG UUID               z8JP5s-lfRw-uKo8-DXAP-XWGe-aKra-xug9Nn


Enough insanity for today :)

I won´t mkfs.xfs on it, the 20 GiB of the just filesystem wouldn´t be 
enough.

Thanks,
-- 
Martin 'Helios' Steigerwald - http://www.Lichtvoll.de
GPG: 03B0 0D6C 0040 0710 4AFA  B82F 991B EAAC A599 84C7

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