Little UFS2 FAQ
Chris Pepper
pepper at reppep.com
Sun Apr 27 22:47:16 UTC 2003
At 2:17 AM -0400 2003/04/26, Jim Brown wrote:
>I've marked it up and posted it at http://sixshooter.v6.thrupoint.net/jeroen/faq.html
>There doesn't seem to be a good 'home' for this poor child- perhaps tacked onto
>http://www.freebsd.org/releases/5.0R/errata.html somewhere?
>
>
>If anyone would like the markup it's at
>http://sixshooter.v6.thrupoint.net/jeroen/Little_UFS_FAQ.sgml.
I've taken a look at the FAQ. My suggested patch is at the bottom of this message, but there are a few bits I don't have proposed fixes for.
Program names (like fsck) need to be tagged.
> <qandaentry>
> <question id="UFS-diff-FFS">
> <para>What is the difference between UFS and FFS?</para>
> </question>
> <answer>
> <para>UFS (and UFS2) define on-disk data layout. FFS sits on
> top of UFS (1 or 2) and provides directory structure information,
> etc, etc. This FAQ is about a revision of UFS named UFS2.</para>
> </answer>
> </qandaentry>
This explanation is much needed, but not detailed enough. Are they both really considered 'file systems'?
> <qandaentry>
> <question id="UFS2-FreeBSD">
> <para>What is the UFS2 status on FreeBSD?</para>
> </question>
> <answer>
> <para>As of FreeBSD-CURRENT 2003/04/20, &man.newfs.8 and
> &man.sysinstall.8 will create UFS2 file systems by default.
> Users wanting to create UFS1 file systems for whatever reason
> (interoperability with earlier versions, etc.) should be sure to
> employ the <option>-O1</option> flag to &man.newfs.8,
> or hit <command>1</command> in the label editor in
> &man.sysinstall.8 to select UFS1.</para>
>
> <note><para>PC98 machines are excempt and still default
> to UFS1. See "On which platforms can UFS2 be used for the root filesystem?"</para>
> </note>
> </answer>
> </qandaentry>
State whether fsck is UFS2-friendly.
NetBSD mentions should include the version when UFS2 was introduced.
Chris Pepper
--- Little_UFS_FAQ.sgml Sun Apr 27 16:04:00 2003
+++ Little_UFS_FAQ.sgml.fixed Sun Apr 27 18:44:29 2003
@@ -141,7 +141,7 @@
<para>Addition of per-inode extended attribute extent</para>
</listitem>
<listitem>
- <para>Lazy inode initialization (watch newfs(8) fly)</para>
+ <para>Lazy inode initialization (watch &man.newfs.8 fly)</para>
</listitem>
</itemizedlist>
</para>
@@ -220,7 +220,7 @@
<answer>
<para>UFS2 has the potential to be faster for really large files
by using jumbo blocks, but the code to do that has yet to be
- written. Additionally, because inodes lazily initialized in UFS2,
+ written. Additionally, because inodes are lazily initialized in UFS2,
&man.newfs.8 runs much faster. Other than that, UFS2 performance should
not significantly differ from UFS1.</para>
</answer>
@@ -231,16 +231,16 @@
<para>What is the UFS2 status on FreeBSD?</para>
</question>
<answer>
- <para>As of 2003/04/20, &man.newfs.8 and &man.sysinstall.8 will
- create UFS2 file systems by default, unless explicitly specified.
+ <para>As of FreeBSD-CURRENT 2003/04/20, &man.newfs.8 and
+ &man.sysinstall.8 will create UFS2 file systems by default.
Users wanting to create UFS1 file systems for whatever reason
- (interoperability with earlier versions, etc) should be sure to
+ (interoperability with earlier versions, etc.) should be sure to
employ the <option>-O1</option> flag to &man.newfs.8,
or hit <command>1</command> in the label editor in
&man.sysinstall.8 to select UFS1.</para>
- <note><para>PC98 machines machines are excempt and still default
- to UFS1. See "On which platforms can UFS2 be used as root filesystem?"</para>
+ <note><para>PC98 machines are excempt and still default
+ to UFS1. See "On which platforms can UFS2 be used for the root filesystem?"</para>
</note>
</answer>
</qandaentry>
@@ -252,43 +252,46 @@
<answer>
<para>As of 2003/04/02 UFS2 is not (yet) the default type for
FFS filesystems. &man.newfs.8 will create a normal FFS filesystem
- by default. If you want an UFS2 fileystem, specify <option>-O 2</option>
+ by default. If you want a UFS2 fileystem, specify <option>-O 2</option>
as an option.</para>
- <para>No additional kernel options are needed for UFS2 support,
+ <para>No additional kernel options are needed for UFS2 support;
it's contained within the FFS code.</para>
- <para>Please note that older fsck binaries will complain a bit
- about filesystems if you boot a new kernel, because of some superblock
- changes. This is harmless. However, if you have 1.6 fsck binaries, they
+ <para>Please note that older &man.fsck.8 binaries will complain a bit
+ about UFS2 filesystems, because of some superblock
+ changes. This is harmless. However, if you have 1.6 &man.fsck.8 binaries, they
will signal a fatal superblock mismatch with the first alternate,
- because they compare too many fields (evenones that aren't useful).
- This is annoying, and I'd advise peole to upgrade their fsck_ffs
- binary before using a new kernel. 1.6.1 will have an fsck
- thatis forward compatible. Again, none of this signals actual
- filesystem damage, but it's still annoying.</para>
+ because they compare too many fields (even ones that aren't useful).
+ This is annoying, and pepole should upgrade their &man.fsck_ffs.8
+ binaries before using UFS2. &man.fsck_ffs.8 1.6.1 will be
+ fully UFS2 compatible.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="UFS2-root">
- <para>On which platforms can UFS2 be used as root filesystem?</para>
+ <para>On which platforms can UFS2 be used for the root filesystem?</para>
</question>
<answer>
<para>The answer to this is defined by /boot/loader. FreeBSD
- Alpha, IA64, and Sparc have no problems.</para>
+ Alpha, IA64, and SPARC have no problems.</para>
+
<para>On FreeBSD i386, the answer is yes, modulo the restriction
- that your root filesystem cannot be larger than 1.5TB.
- (David Schultz et al. proposed a patch to remove this limitation.)
- FreeBSD PC98 does not support UFS2 root partitions and it is
- unknown if work is underway to address this.</para>
- <para>NetBSD support I don't know anything about..</para>
+ that the root filesystem cannot be larger than 1.5TB.
+ David Schultz, et al., have proposed a patch to remove this
+ limitation. FreeBSD PC98 does not support UFS2 root
+ partitions and it is unknown if work is underway to address
+ this.</para>
+
+ <para>NetBSD support is unknown to the author of this
+ document as of this writing.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="conversion-tool">
- <para>Is there a UFS to UFS2 conversion tool?</para>
+ <para>Is there a UFS1 to UFS2 conversion tool?</para>
</question>
<answer>
<para>No, but see next question.</para>
@@ -297,10 +300,10 @@
<qandaentry>
<question id="dump">
- <para>Will "dump" on UFS and "restore" on UFS2 filesystem work?</para>
+ <para>Can a UFS1 dump be restored to a UFS2 filesystem?</para>
</question>
<answer>
- <para>Yes, that will work. (Example invocation would be nice. Anyone?)</para>
+ <para>Yes, this will work. (Example invocation would be nice. Anyone?)</para>
</answer>
</qandaentry>
@@ -332,6 +335,7 @@
<para>You need a loader and bootblocks that support UFS2.
Try using <command>disklabel -B</command></para>
+
<blockquote>
<attribution>From Daniel Sobral</attribution>
<para>You need a new boot block.
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