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FS#11190 - Make 256 the default inode_size for ext2/3 partitions

Attached to Project: Arch Linux
Opened by Greg (dolby) - Monday, 11 August 2008, 20:09 GMT
Last edited by Aaron Griffin (phrakture) - Monday, 01 December 2008, 22:42 GMT
Task Type Bug Report
Category Packages: Core
Status Closed
Assigned To Aaron Griffin (phrakture)
Tom Killian (tomk)
Andreas Radke (AndyRTR)
Architecture All
Severity High
Priority Normal
Reported Version None
Due in Version Undecided
Due Date Undecided
Percent Complete 100%
Votes 0
Private No


Description: We should use the default mke2fs.conf file provided by upstream & make 256 the default inode_size for ext2/3 partitions.
That will ease the transition to the new ext4 filesystem. Only problem seems to be grub 0.97 which doesnt support that size & grub2 is still not stable enough. I dont know if does just that, here is a relevant bug report from debian which contains links to some patches from fedora.

PS. Assigning it to TomK which holds e2fsprogs, AndyRTR for grub and Aaron to take a look at it. Hopefully that will speed things up.
IMO its pretty important for newly created ext3 partitions to have 256 inode_size.

This task depends upon

Closed by  Aaron Griffin (phrakture)
Monday, 01 December 2008, 22:42 GMT
Reason for closing:  Fixed
Additional comments about closing:  See final comment. Default changed upstream
Comment by Glenn Matthys (RedShift) - Monday, 11 August 2008, 20:38 GMT
This is really patching for features and not patching for problems. Big -1 from me. I don't see what this helps in easing the transition from ext3 to ext4?
Comment by Greg (dolby) - Monday, 11 August 2008, 20:59 GMT
Ext3 partitions created with the mke2fs.conf in the Archlinux package will be created with inode_size 128 . That means when ext4 is stable and the default they will have to reformat their partitions cause as man mke2fs says:
" -i bytes-per-inode
Specify the bytes/inode ratio. mke2fs creates an inode for every bytes-per-inode bytes of space on the disk. The larger the bytes-per-inode ratio, the fewer inodes will be created. This value generally shouldn't be smaller than the blocksize of the filesystem, since then too many inodes will be made. Be warned that is not possible to expand the number of inodes on a filesystem after it is created, so be careful deciding the correct value for this parameter."

Well, i dont like the patching either but the other solution would be to replace grub with grub2. Or go with lilo which has no problem with it.
Comment by Xavier (shining) - Tuesday, 12 August 2008, 06:14 GMT Comment by Greg (dolby) - Tuesday, 12 August 2008, 12:38 GMT
Thanks very much Xavier.
brain0 mentions:
Adding the patch to grub is a good thing, however: Default inode size of 256 will result in:
- Incompatibility to older distributions
- Incompatibility to live CDs
- Incompatibility to grub versions not coming from Arch
- Incompatibility to filesystem drivers for other operating systems

What happens then when ext4 is the default? 1,2 & probably 4 will still be valid for quite a long time. The way Archlinux works, as a rolling release distro, install once and never again, when will changes like this be incorporated? They have to at some point..
It reminds me  FS#10910  and especially Pierre's answer in a way.

Comment by Xavier (shining) - Tuesday, 12 August 2008, 13:01 GMT
I am a bit confused by this bug report. What do you mean by the ext4 transition?
ext3 has been the "default" filesystem for years (I think it is the most widely used one, and the most often used by default by distrib), and yet ext2 is still around and perfectly working. Isn't it the same with ext4?
Also some people still prefer using ext2 in some circumstances where they don't need the overhead of journaling.

In my opinion, there is no transition to consider here. People who wants to switch filesystem are free to reinstall, or to backup and reformat.
And users open to the future which don't care about backward compatibility are also free to use 256 inode_size anyway.
I don't know but it looks like making that change would do more harm than good.

Finally, I don't understand Pierre's answer in  FS#10910 
Comment by Greg (dolby) - Monday, 18 August 2008, 16:46 GMT
I mean that users should be able to convert their ext3 partitions to ext4 when time comes.
The only thing that's gonna prevent em from doing so is the 128 inode_size.
Anywway none of the developers i assigned it to bothered to response and since this has already been discussed at the mailing list i guess their minds are made up.
Feel free to close this if you have nothing more to add.
Comment by Matt Beisser (beissemj) - Saturday, 20 September 2008, 04:19 GMT
+1 Developers
+1 Xavier

This is a bootloader problem, not a filesystem problem. If someone wants to convert their existing filesystem to ext4, that's their business and their problem. Changing the defaults of two different filesystems because a new one uses a different default? How does that even make sense?
Comment by Tom Killian (tomk) - Friday, 28 November 2008, 12:43 GMT
Reviewing bugs with my name on them, and this one is confusing. The upstream mke2fs.conf that we are now shipping shows inode_size = 256 in the [defaults] section, so can I mark this as fixed? If so, what has happened to the concerns raised above about setting the default at 256?