A few ext4 questions

[Fintan]

Awaiting the release of JJ I was wondering about a few things concerning ext4.

- Can I migrate from fat32 to ext4 without loosing data.
Or do I need to format a partition as ext4 and then move my data over?

All my data is on a separate partition /data and is fat32 because I need that for my vmware xp guest system.

- Can windows read / write to ext4?

This not urgent but maybe helpful not just for myself.

[dibl]

Re: A few ext4 questions

@Fintan, I think the answer depends on what you mean by "migrate".

I just partitioned a new 1T Western Digital hard drive with four ext4 partitions last night, and learned this much:

1. Kubuntu 8.10, with a 2.6.27 kernel, cannot read or write to the filesystem. It is seen by fdisk as an ext4 filesystem, but it won't mount or read/write.

2. sidux, with a 2.6.28 kernel, has no problem at all -- it acts just like any other partition. I mounted a couple of the new partitions, and copied a ton of video and music files off partitions with other filesystems (XFS and ext3) to the new drive.

So, when or if you have a Linux system running a 2.6.28 kernel, then you can certainly use ext4 partitions just the same as you use ext3, ext2, FAT32, XFS, or JFS. However, you can only "upgrade" an ext3 to an ext4, and I would have to study the manual to learn how to do that. Otherwise you must "format" to ext4, which of course will write over any previous data and filesystem.

I'm waiting for the right moment (9.04 Beta) to install Kubuntu on an ext4 partition that I made for that purpose, but it was interesting to see that, for storage purposes, it seems to work perfectly.

I can't answer the question about Windows reading/writing directly. My plan is to use my VMware Player Win XP machine, and get to the other parts of my system via Samba networking -- that way Windows doesn't know what those other filesystems are. I suspect Windows will NOT read or write to ext4, unless the "Ext2ifs.sys" driver will still work with it. I kinda doubt it.

[Fintan]

Re: A few ext4 questions

Thank you dible.

However, you can only "upgrade" and ext3 to an ext4, and I would have to study the manual to learn how to do that. Otherwise you must "format" to ext4, which of course will write over any previous data and filesystem.

I think I used the wrong term. I meant "upgrade" to ext4 from fat32 without losing data.
I believe this is possible for ext3 to ext4.
So that makes sense.

I can't answer the question about Windows reading/writing directly. My plan is to use my VMware Player Win XP machine, and get to the other parts of my system via Samba networking -- that way Windows doesn't know what those other filesystems are. I suspect Windows will NOT read or write to ext4, unless the "Ext2ifs.sys" driver will still work with it. I kinda doubt it.

Well, I am using samba for that right now so that shouldn't be a problem.

I will try the format and copy / move method and see what happens

[hegemon_8]

Re: A few ext4 questions

Hi, I'm not sure about the migration, But i have Kubuntu 9.04 JJ (Alpha 3) And i had WinVista And Win7(Beta) on 2 other partitions. They were ok with my Interpid Ibex on ext3, using Ext2ifs (Sorry, Ext2ifs didn't work on my Win7) but Vista didn't like my Jaunty with ext 4.
Jaunty works with ext4 very well (beside some Jaunty problems with my ATI Graphics, oh well, its Alpha after all)
But there is no problem with R/W ext3, ext4,NTFS. Sorry i cant help You more, but hope, it was handy for You.

[Fintan]

Re: A few ext4 questions

Thank you hegamon,
I did a ext4 format of a partition and copied over my most important files from my fat32. It worked fine exept for taking a long time and eating up all my cpu /ram during the process. Well there were almost 80 GIGs.

Sharing ext4 works fine through samba with a vm xp guest. Unfortunately vmware-player breaks the JJ Internet connection upon reboot after installation and I had to uninstall it.

So I'll wait for the beta/final to continue on this path.

[hegemon_8]

Re: A few ext4 questions

I cant wait final release my self By the way, I've fixed my graphics problem using open source ATI driver after uninstalling prop. one. God bless Launchpad

[3vi1]

Re: A few ext4 questions

I did a ext4 format of a partition and copied over my most important files from my fat32...

ACK!!!! Do *not* use Ext4 on this alpha OS for anything important at this point. See https://bugs.launchpad.net/ubuntu/+s...ux/+bug/317781 for details.

[dibl]

Re: A few ext4 questions

ACK!!!! Do *not* use Ext4 on this alpha OS for anything important at this point. See https://bugs.launchpad.net/ubuntu/+s...ux/+bug/317781 for details.

Bummer! I wonder if the problem is limited to the root filesystem? Kinda hard to tell reading the bug thread.

Well, I guess it's good that there are a few weeks to beat on it before the release date!

[Fintan]

Re: A few ext4 questions

I haven't experienced any problems yet. Any way I just copied over not moved over

[3vi1]

Re: A few ext4 questions

Bummer! I wonder if the problem is limited to the root filesystem? Kinda hard to tell reading the bug thread.

Well, I guess it's good that there are a few weeks to beat on it before the release date!

No... it's not limited to the root. I found that out the hard way when we had a power outage (test machine wasn't on a UPS at the time). I've also tested by hard-booting (reset button) and had files in my home directory (and subdirectories) trashed with zero-length. I had no such problems when the same machine was running Intrepid on Ext3.

There doesn't appear to be any corruption at all if you can shut the machine down normally each time, so put your box on a UPS and if you lose all keyboard/mouse response be sure to try SSH from another box before using reset!

I'm just keeping my important stuff on an external non-Ext4 drive for now. If it's not fixed by release, I'll re-install as Ext3 again.

[dibl]

Re: A few ext4 questions

I run on a UPS, but it just passed its second birthday -- I may need to re-think my plans to install 9.04 Beta on an ext4 filesystem, and for using ext4 partitions for my (substantial) data. I've already had the experience of an XFS root filesystem falling apart -- not sure I want to deal with that again.

[toad]

Re: A few ext4 questions

fwiw - I've been running an ext4 system successfully for some time now. At first I thought the bug affects only the buntu family but a Gentoo user reported similar behaviour. Cross my fingers and hope to die it doesn't happen to me. Having said that, I have been monitoring a very busy ArchLinux community and there are no reports of any such off-stuff happening...

[Zerix01]

Re: A few ext4 questions

Well I have read through that massive bug report / ext4 rant. It looks like kernel 2.6.30 will have some fixes that make ext4 act more like ext3. This will also slow down ext4. The key problem has to do with the fact that ext4 does delayed allocation which also will effect XFS ZFS and Reiser4 which all do delayed allocation. No mention of Reiser3 (my fs of choice, but I was looking to replace it with ext4 or btrfs due to lack of Reiser support).

One of the developers making kernel patches blames the issue on application developers not using fsync to commit the files to the fs when they must be written (rather than being delayed). I may have missed something but this really does not explain why the old version of the file gets zeroed out while the new version gets lost due to sudden power loss. Possibly the journal has meta data for the new version in it but the new version was lost so now the old version is invalid due to the meta data saying so.

I haven't had a kernel freeze for a long time. I do however have my X-server freeze up a lot mainly due to a CUDA program I run. But despite not having control over the GUI I have my system set to soft power off, so if I press, but do not hold, the power button then the kernel picks up a shutdown command and safely shuts down committing all non synced data. Another user also suggested ctrl + alt + sysrq + s will do a sync (and maybe shutdown, it could be that just needs to be done before a hard power off). If your kernel is locked up then I guess all bets are off. I'm wondering how many people are interpreting an X-server lock up for a kernel lock up? The last few times I remember a kernel lock my num lock and caps lock lights on my keyboard were flashing. If that is not happening I can normally do my clean soft power off, despite no other control over the system.

[dibl]

Re: A few ext4 questions

Here's an informative article on the topic:

http://www.h-online.com/open/Ext4-da...--/news/112892

It covers the question of the "0" file sizes.

Even though the full solution "alloc_on_commit" won't be available until 2.6.30 kernel version, I'm going ahead with my plan to install 9.04 Beta on an ext4 partition, when it comes out next week. But I won't be saving any critical data on that partition for awhile.

[Detonate]

Re: A few ext4 questions

I've been playing with JJ with ext4 a couple of weeks now. No file system problems. But it is aggravating that i can't mount the JJ partition in II or HH. I like to be able to edit files on my other distros. I always keep at least two distros installed at all times just for this purpose. Can't tell you how many times this has saved me.