[linux-lvm] large logical volumes

[Guido Vettoretti]

Dan Pritts wrote:

>On Fri, Apr 29, 2005 at 04:35:02PM -0400, Guido Vettoretti wrote:
>  
>
>>32-bit machines:
>>ext3 : 2Tb (I managed to create a 4TB fs for some reason)
>>    
>>
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>  
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>I'm not sure this is true - i think that this limit was there but was
>removed in newer versions of ext2/3
>
>  
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I haven't heard anything about the new versions but I was workiing with 
kernel 2.6.9, and the number of block groups would roll over to 0 when I 
specified a number greater than 32768. Thus the max limitation seemes to 
be 4096(bytes/block)*32768(blocks/group)*32768(blockgroups) =  4TB

[root at cyclone ~]# mkfs -t ext3 /dev/vol0/lvol0
mke2fs 1.35 (28-Feb-2004)
max_blocks 4294967295, rsv_groups = 0, rsv_gdb = 1024
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
512016384 inodes, 1024002048 blocks
8250429 blocks (0.81%) reserved for the super user
First data block=0
Maximum filesystem blocks=1027604480
31251 block groups
32768 blocks per group, 32768 fragments per group


>>ext3: 2Tb (? not sure about this one)
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>I have created larger filesystems on 64-bit.
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>  
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>>One of the hardware support people said there was a 2Tb limit on the 
>>SCSI protocol (not sure about this), 
>>    
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>More or less true, but some newer hardware and device drivers 
>have fixed this.  The keyword you need to look for is "64-bit LBA".
>
>I've had success with an Atto celerity fibre channel adapter and
>an infortrend-based RAID on x86_64.  However, each one needed a
>firmware/driver update from what was shipped to me in December of
>last year to work.
>
>  
>
This is useful info,
Thanks
Guido
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