[PATCH] doc: Suggest decreasing bytes per inode.

Mohammed Sadiq wrote on 29 Sep 2017 05:29

Recipients:(address . guix-patches@gnu.org)

Message-ID:2026981815.9444.1506655757552@webmail.mailhostbox.com

This may not be optimal. But I believe this might be good.

On my system (with 21 GiB root partition), I was always getting
"No space left on device" error while `df -h' was reporting 7 GiB
of free space. After further investigation I found that the inode
space was filled (df -i).

From 9b44896352f63f1417e241a193267a6ffdb72017 Mon Sep 17 00:00:00 2001

By default bytes per inode is 16KiB. As the store files can be really

small the inode space may get filled and errors regarding no empty space

begins to appear.

Reducing the size to 8KiB has an overhead of about 16MiB per GiB

reserved for inode, better than having lots of cannot be used partition

space.

* doc/guix.texi (Disk Partitioning): Suggest to decrease bytes per inode

for small partitions.

---

doc/guix.texi | 11 +++++++++++

1 file changed, 11 insertions(+)

Toggle diff (24 lines)diff --git a/doc/guix.texi b/doc/guix.texi
index 1b329d255..a150fa024 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -7998,6 +7998,17 @@ partition lives at @file{/dev/sda1}, a file system with the label
 mkfs.ext4 -L my-root /dev/sda1
 @end example
 
+As the store (@pxref{The Store}) shall be having lots of directories,
+symbolic links, and small files, the inode space may run out before
+the disk space is filled, especially if the partition size is small.
+Decreasing the bytes per inode shall be better to avoid related issues.
+So, with partition @file{/dev/sda1}, and with a label @code{my-root},
+bytes per inode can be set with:
+
+@example
+mkfs.ext4 -L my-root -i 8192 /dev/sda1
+@end example
+
 @cindex encrypted disk
 If you are instead planning to encrypt the root partition, you can use
 the Cryptsetup/LUKS utilities to do that (see @inlinefmtifelse{html,
-- 
2.14.1

Ludovic Courtès wrote on 3 Oct 2017 15:14

Recipients:(name . Mohammed Sadiq)(address . sadiq@sadiqpk.org)(address . 28638@debbugs.gnu.org)

Message-ID:87tvzg74qs.fsf@gnu.org

Hello,

Mohammed Sadiq <sadiq@sadiqpk.org> skribis:

Toggle quote (5 lines)

> On my system (with 21 GiB root partition), I was always getting

> "No space left on device" error while `df -h' was reporting 7 GiB

> of free space. After further investigation I found that the inode

> space was filled (df -i).

[...]

Toggle quote (10 lines)> +As the store (@pxref{The Store}) shall be having lots of directories,
> +symbolic links, and small files, the inode space may run out before
> +the disk space is filled, especially if the partition size is small.
> +Decreasing the bytes per inode shall be better to avoid related issues.
> +So, with partition @file{/dev/sda1}, and with a label @code{my-root},
> +bytes per inode can be set with:
> +
> +@example
> +mkfs.ext4 -L my-root -i 8192 /dev/sda1

Are you sure that this suggestion helps fix what you experienced?

I’ve used ext4 partitions much bigger than this but I’ve never needed to

pass “-i 8192” or similar.

Could it be that the ENOSPC you experienced was due to something else,

or on some other partition?

Thanks,

Ludo’.

Mohammed Sadiq wrote on 3 Oct 2017 16:05

Recipients:(name . Ludovic Courtès)(address . ludo@gnu.org)(address . 28638@debbugs.gnu.org)

Message-ID:587759055.67303.1507039513640@webmail.mailhostbox.com

Toggle quote (4 lines)

> On October 3, 2017 at 6:44 PM Ludovic Courtès <ludo@gnu.org> wrote:

> Hello,

Hello,

Toggle quote (3 lines)

> I’ve used ext4 partitions much bigger than this but I’ve never needed to

> pass “-i 8192” or similar.

The issue happens when lots of small files are stored in store.

It may be possible to reproduce this by creating a separate partition

for /gnu/store with size around 5-10 GiB (I haven't tried that way though).

Toggle quote (2 lines)

> Could it be that the ENOSPC you experienced was due to something else,

> or on some other partition?

Idk. This same error was shown when downloading a file in icecat or copying

a file in nautilus in home dir.

But of course, this patch can wait, until some others have the same issue.

Anyway, note that if no space error is shown, it can either be disk space

filled (df -h) or inode space filled (df -hi).

Thanks

Leo Famulari wrote on 3 Oct 2017 16:19

Recipients:(name . Ludovic Courtès)(address . ludo@gnu.org)

Message-ID:20171003141950.GA23431@jasmine.lan

On Tue, Oct 03, 2017 at 03:14:35PM +0200, Ludovic Courtès wrote:

Toggle quote (16 lines)> Mohammed Sadiq <sadiq@sadiqpk.org> skribis:
> > +As the store (@pxref{The Store}) shall be having lots of directories,
> > +symbolic links, and small files, the inode space may run out before
> > +the disk space is filled, especially if the partition size is small.
> > +Decreasing the bytes per inode shall be better to avoid related issues.
> > +So, with partition @file{/dev/sda1}, and with a label @code{my-root},
> > +bytes per inode can be set with:
> > +
> > +@example
> > +mkfs.ext4 -L my-root -i 8192 /dev/sda1
> 
> Are you sure that this suggestion helps fix what you experienced?
> 
> I’ve used ext4 partitions much bigger than this but I’ve never needed to
> pass “-i 8192” or similar.

I've also not run out of inodes on my ext4 system that was set up with

Debian's defaults.

Also, it may be better to recommend creating the filesystem with more

inodes than usual, rather than reducing the size of the inodes. From the

man page mkfs.ext4(8):

-N number-of-inodes

Overrides the default calculation of the number of inodes that

should be reserved for the filesystem (which is based on the

number of blocks and the bytes-per-inode ratio). This allows the

user to specify the number of desired inodes directly.

But then you are really asking for too much expertise when installing

Guix, in my opinion.

Ludovic Courtès wrote on 7 Oct 2017 22:42

control message for bug #28638

Recipients:(address . control@debbugs.gnu.org)

Message-ID:87sheuita2.fsf@gnu.org

tags 28638 wontfix

close 28638

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