Re: Maximum file system size of XFS?

Martin Steigerwald
2013-03-11T21:57:03Z

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