Recommended partition scheme for nilfs2

Recommended partition scheme for nilfs2

[LinuxBSDos.com]

Hi,

A couple of Linux distributions now have nilfs2 as an optional file system
during installation and I just want to find out what the minimum number of
partitions required for a nilfs2-based installation is.

Is it necessary to create separate partitions for the major file systems,
or does nilfs2 require just one root file system directory? Is /home on a
separate partition necessary?

Lastly, can I encrypt a nilfs2 partition?

Thanks,

--
Fini D.

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Re: Recommended partition scheme for nilfs2

[Ryusuke Konishi]

Hi,
On Mon, 4 Jul 2011 13:28:39 -0600, "LinuxBSDos.com" wrote:
> 
> Hi,
> 
> A couple of Linux distributions now have nilfs2 as an optional file system
> during installation and I just want to find out what the minimum number of
> partitions required for a nilfs2-based installation is.
> 
> Is it necessary to create separate partitions for the major file systems,
> or does nilfs2 require just one root file system directory? Is /home on a
> separate partition necessary?

nilfs2 can be used as a root filesystem and it is bootable from recent
grub2.  I'm using nilfs2 for the root filesystem on my ubuntu-natty
laptop.

One restriction is that nilfs2 does not support swap file, so users
need at least two partitions, swap and root.

/home is not necessary to be a separate partition.

> Lastly, can I encrypt a nilfs2 partition?

nilfs2 itself does not support encryption.  Instead, it can be used
together with ecryptfs or dm-crypt.

Thanks,
Ryusuke Konishi

> Thanks,
> 
> --
> Fini D.
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-nilfs" in
> the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
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Re: Recommended partition scheme for nilfs2

[LinuxBSDos.com]

Thank you.

With regards to /home, will there be a negative impact on the way nilfs2
works if /home is on a separate partition?

On Ubuntu and nilfs2, Ubuntu's installer does not have nilfs2 as a file
system option, how did you install Natty N. on nilfs2?

I know these are not dev-related questions, but I'm planning on writing
several nilfs2-related tutorials, and need to know exactly how a disk
should be partitioned for it.

Thanks,


--
Fini D.



> Hi,
> On Mon, 4 Jul 2011 13:28:39 -0600, "LinuxBSDos.com" wrote:
>>
>> Hi,
>>
>> A couple of Linux distributions now have nilfs2 as an optional file
>> system
>> during installation and I just want to find out what the minimum number
>> of
>> partitions required for a nilfs2-based installation is.
>>
>> Is it necessary to create separate partitions for the major file
>> systems,
>> or does nilfs2 require just one root file system directory? Is /home on
>> a
>> separate partition necessary?
>
> nilfs2 can be used as a root filesystem and it is bootable from recent
> grub2.  I'm using nilfs2 for the root filesystem on my ubuntu-natty
> laptop.
>
> One restriction is that nilfs2 does not support swap file, so users
> need at least two partitions, swap and root.
>
> /home is not necessary to be a separate partition.
>
>> Lastly, can I encrypt a nilfs2 partition?
>
> nilfs2 itself does not support encryption.  Instead, it can be used
> together with ecryptfs or dm-crypt.
>
> Thanks,
> Ryusuke Konishi
>
>> Thanks,
>>
>> --
>> Fini D.
>>
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-nilfs"
>> in
>> the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> --
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> the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>


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Re: Recommended partition scheme for nilfs2

[Ryusuke Konishi]

On Wed, 6 Jul 2011 06:29:53 -0600, "LinuxBSDos.com" wrote:
> 
> Thank you.
> 
> With regards to /home, will there be a negative impact on the way nilfs2
> works if /home is on a separate partition?

Usually this is a good usage.

Possible demerits are:

 * We have to mount and access snapshots separately per partition.

 * Checkpoint numbers increase differently if we use two or more nilfs
   partitions.  This makes it a bit troublesome to choose consistent
   snapshots for multiple nilfs2 partitions.

 * User needs to specify a device argument for lscp and other snapshot
   commands for multiple nilfs2 partitions.

   The current nilfs utilities does not provide the way to specify a
   target partition with a directory argument.

 * GC daemons run and reside for each nilfs2 partition, and this may
   require more memory and cpu time.  Usually this is not an issue
   because GC daemons will sleep while having enough free space.


As long as applying nilfs2 only to /home, I think there is no
mentionable demerit except the system is not protected with the
automatic checkpoints/snapshots.


> On Ubuntu and nilfs2, Ubuntu's installer does not have nilfs2 as a file
> system option, how did you install Natty N. on nilfs2?

I cannot remember how I built the current natty environment, but
usually I do that manually with debootstrap program.  The following is
a copy of my memorandum showing a rough scheme:

 1) Make a bootable usb pendrive.

 2) Install nilfs-utils and debootstrap in it.

 3) Boot from the usb memory and format the main drive with nilfs2:

   # mkfs -t nilfs2 /dev/sda8

 4) Mount it and run debootstrap.

   # mount -t nilfs2 /dev/sda8 /nilfs
   # debootstrap --arch amd64 natty /nilfs/ http://xxx.xxx.xx.xx/xxxxx/ubuntu/
 
 5) Edit /nilfs/etc/fstab.

 6) Edit or copy /etc/hosts.

 7) Copy /home as needed.

   # rsync -ax /home/ /nilfs/home/

 8) Do chroot

   # chroot /nilfs /bin/bash
   # mount -t proc none /proc
   # mount -t sysfs none /sys
   # mount /dev/sda8 /boot  (if using a separate boot partition)

 9) Set root password

   # passwd

 10) Make an acount

   # groupadd -g 1000 <my-user-name>
   # useradd -g <my-user-name> -u 1000 -c "My Name" -s /bin/bash <my-user-name>
   # passwd <my-user-name>

 11) Edit /nilfs/etc/apt/sources.list

 12) Set timezone

   # dpkg-reconfigure tzdata

 13) Install packages

   # apt-get update
   # apt-get install rsync ssh openssh-server sudo gcc make git-core
     automake autoconf aptitude ...

 14) Build and install nilfs-utils

 15) Manually build and install util-linux-ng which supports nilfs2.
     This is required to mount nilfs2 partitions by a UUID or a LABEL.

 16) Install and setup grub2, and run update-grub program

 17) Reboot

 18) Install desktop environment


I think this needs trial and error for natty since this memorandum was
originally made for Debian.


Regards,
Ryusuke Konishi

> I know these are not dev-related questions, but I'm planning on writing
> several nilfs2-related tutorials, and need to know exactly how a disk
> should be partitioned for it.
> 
> Thanks,
> 
> 
> --
> Fini D.
> 
> 
> 
> > Hi,
> > On Mon, 4 Jul 2011 13:28:39 -0600, "LinuxBSDos.com" wrote:
> >>
> >> Hi,
> >>
> >> A couple of Linux distributions now have nilfs2 as an optional file
> >> system
> >> during installation and I just want to find out what the minimum number
> >> of
> >> partitions required for a nilfs2-based installation is.
> >>
> >> Is it necessary to create separate partitions for the major file
> >> systems,
> >> or does nilfs2 require just one root file system directory? Is /home on
> >> a
> >> separate partition necessary?
> >
> > nilfs2 can be used as a root filesystem and it is bootable from recent
> > grub2.  I'm using nilfs2 for the root filesystem on my ubuntu-natty
> > laptop.
> >
> > One restriction is that nilfs2 does not support swap file, so users
> > need at least two partitions, swap and root.
> >
> > /home is not necessary to be a separate partition.
> >
> >> Lastly, can I encrypt a nilfs2 partition?
> >
> > nilfs2 itself does not support encryption.  Instead, it can be used
> > together with ecryptfs or dm-crypt.
> >
> > Thanks,
> > Ryusuke Konishi
> >
> >> Thanks,
> >>
> >> --
> >> Fini D.
> >>
> >> --
> >> To unsubscribe from this list: send the line "unsubscribe linux-nilfs"
> >> in
> >> the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
> >> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> > --
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> > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> >
> 
> 
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Re: Recommended partition scheme for nilfs2

[LinuxBSDos.com]

Thanks a bundle. That pretty much addresses all I/we need to know about
disk partitioning per nilfs2.


--
Fini D.


> On Wed, 6 Jul 2011 06:29:53 -0600, "LinuxBSDos.com" wrote:
>>
>> Thank you.
>>
>> With regards to /home, will there be a negative impact on the way nilfs2
>> works if /home is on a separate partition?
>
> Usually this is a good usage.
>
> Possible demerits are:
>
>  * We have to mount and access snapshots separately per partition.
>
>  * Checkpoint numbers increase differently if we use two or more nilfs
>    partitions.  This makes it a bit troublesome to choose consistent
>    snapshots for multiple nilfs2 partitions.
>
>  * User needs to specify a device argument for lscp and other snapshot
>    commands for multiple nilfs2 partitions.
>
>    The current nilfs utilities does not provide the way to specify a
>    target partition with a directory argument.
>
>  * GC daemons run and reside for each nilfs2 partition, and this may
>    require more memory and cpu time.  Usually this is not an issue
>    because GC daemons will sleep while having enough free space.
>
>
> As long as applying nilfs2 only to /home, I think there is no
> mentionable demerit except the system is not protected with the
> automatic checkpoints/snapshots.
>
>
>> On Ubuntu and nilfs2, Ubuntu's installer does not have nilfs2 as a file
>> system option, how did you install Natty N. on nilfs2?
>
> I cannot remember how I built the current natty environment, but
> usually I do that manually with debootstrap program.  The following is
> a copy of my memorandum showing a rough scheme:
>
>  1) Make a bootable usb pendrive.
>
>  2) Install nilfs-utils and debootstrap in it.
>
>  3) Boot from the usb memory and format the main drive with nilfs2:
>
>    # mkfs -t nilfs2 /dev/sda8
>
>  4) Mount it and run debootstrap.
>
>    # mount -t nilfs2 /dev/sda8 /nilfs
>    # debootstrap --arch amd64 natty /nilfs/
> http://xxx.xxx.xx.xx/xxxxx/ubuntu/
>
>  5) Edit /nilfs/etc/fstab.
>
>  6) Edit or copy /etc/hosts.
>
>  7) Copy /home as needed.
>
>    # rsync -ax /home/ /nilfs/home/
>
>  8) Do chroot
>
>    # chroot /nilfs /bin/bash
>    # mount -t proc none /proc
>    # mount -t sysfs none /sys
>    # mount /dev/sda8 /boot  (if using a separate boot partition)
>
>  9) Set root password
>
>    # passwd
>
>  10) Make an acount
>
>    # groupadd -g 1000 <my-user-name>
>    # useradd -g <my-user-name> -u 1000 -c "My Name" -s /bin/bash
> <my-user-name>
>    # passwd <my-user-name>
>
>  11) Edit /nilfs/etc/apt/sources.list
>
>  12) Set timezone
>
>    # dpkg-reconfigure tzdata
>
>  13) Install packages
>
>    # apt-get update
>    # apt-get install rsync ssh openssh-server sudo gcc make git-core
>      automake autoconf aptitude ...
>
>  14) Build and install nilfs-utils
>
>  15) Manually build and install util-linux-ng which supports nilfs2.
>      This is required to mount nilfs2 partitions by a UUID or a LABEL.
>
>  16) Install and setup grub2, and run update-grub program
>
>  17) Reboot
>
>  18) Install desktop environment
>
>
> I think this needs trial and error for natty since this memorandum was
> originally made for Debian.
>
>
> Regards,
> Ryusuke Konishi
>
>> I know these are not dev-related questions, but I'm planning on writing
>> several nilfs2-related tutorials, and need to know exactly how a disk
>> should be partitioned for it.
>>
>> Thanks,
>>
>>
>> --
>> Fini D.
>>
>>
>>
>> > Hi,
>> > On Mon, 4 Jul 2011 13:28:39 -0600, "LinuxBSDos.com" wrote:
>> >>
>> >> Hi,
>> >>
>> >> A couple of Linux distributions now have nilfs2 as an optional file
>> >> system
>> >> during installation and I just want to find out what the minimum
>> number
>> >> of
>> >> partitions required for a nilfs2-based installation is.
>> >>
>> >> Is it necessary to create separate partitions for the major file
>> >> systems,
>> >> or does nilfs2 require just one root file system directory? Is /home
>> on
>> >> a
>> >> separate partition necessary?
>> >
>> > nilfs2 can be used as a root filesystem and it is bootable from recent
>> > grub2.  I'm using nilfs2 for the root filesystem on my ubuntu-natty
>> > laptop.
>> >
>> > One restriction is that nilfs2 does not support swap file, so users
>> > need at least two partitions, swap and root.
>> >
>> > /home is not necessary to be a separate partition.
>> >
>> >> Lastly, can I encrypt a nilfs2 partition?
>> >
>> > nilfs2 itself does not support encryption.  Instead, it can be used
>> > together with ecryptfs or dm-crypt.
>> >
>> > Thanks,
>> > Ryusuke Konishi
>> >
>> >> Thanks,
>> >>
>> >> --
>> >> Fini D.
>> >>
>> >> --
>> >> To unsubscribe from this list: send the line "unsubscribe
>> linux-nilfs"
>> >> in
>> >> the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
>> >> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>> > --
>> > To unsubscribe from this list: send the line "unsubscribe linux-nilfs"
>> in
>> > the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
>> > More majordomo info at  http://vger.kernel.org/majordomo-info.html
>> >
>>
>>
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-nilfs"
>> in
>> the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
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> --
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Re: Recommended partition scheme for nilfs2

[LinuxBSDos.com]

Just one more thing.

For btrfs and other file systems, it is customary to have a separate boot
partition, so that at a minimum, you have 3 partitions - /boot, Swap, and
/. Would that be a problem for nilfs2?

If it is ok to have a separate boot partition, does it make sense to use
nilfs2 on it? Or is it better to use a non-journaling file system, like
Linux Native (ext2) on the boot partition, and nilfs2 on /.

Thanks for your time.


--
Fini D.


>
> Thanks a bundle. That pretty much addresses all I/we need to know about
> disk partitioning per nilfs2.
>
>
> --
> Fini D.
>
>
>> On Wed, 6 Jul 2011 06:29:53 -0600, "LinuxBSDos.com" wrote:
>>>
>>> Thank you.
>>>
>>> With regards to /home, will there be a negative impact on the way
>>> nilfs2
>>> works if /home is on a separate partition?
>>
>> Usually this is a good usage.
>>
>> Possible demerits are:
>>
>>  * We have to mount and access snapshots separately per partition.
>>
>>  * Checkpoint numbers increase differently if we use two or more nilfs
>>    partitions.  This makes it a bit troublesome to choose consistent
>>    snapshots for multiple nilfs2 partitions.
>>
>>  * User needs to specify a device argument for lscp and other snapshot
>>    commands for multiple nilfs2 partitions.
>>
>>    The current nilfs utilities does not provide the way to specify a
>>    target partition with a directory argument.
>>
>>  * GC daemons run and reside for each nilfs2 partition, and this may
>>    require more memory and cpu time.  Usually this is not an issue
>>    because GC daemons will sleep while having enough free space.
>>
>>
>> As long as applying nilfs2 only to /home, I think there is no
>> mentionable demerit except the system is not protected with the
>> automatic checkpoints/snapshots.
>>
>>
>>> On Ubuntu and nilfs2, Ubuntu's installer does not have nilfs2 as a file
>>> system option, how did you install Natty N. on nilfs2?
>>
>> I cannot remember how I built the current natty environment, but
>> usually I do that manually with debootstrap program.  The following is
>> a copy of my memorandum showing a rough scheme:
>>
>>  1) Make a bootable usb pendrive.
>>
>>  2) Install nilfs-utils and debootstrap in it.
>>
>>  3) Boot from the usb memory and format the main drive with nilfs2:
>>
>>    # mkfs -t nilfs2 /dev/sda8
>>
>>  4) Mount it and run debootstrap.
>>
>>    # mount -t nilfs2 /dev/sda8 /nilfs
>>    # debootstrap --arch amd64 natty /nilfs/
>> http://xxx.xxx.xx.xx/xxxxx/ubuntu/
>>
>>  5) Edit /nilfs/etc/fstab.
>>
>>  6) Edit or copy /etc/hosts.
>>
>>  7) Copy /home as needed.
>>
>>    # rsync -ax /home/ /nilfs/home/
>>
>>  8) Do chroot
>>
>>    # chroot /nilfs /bin/bash
>>    # mount -t proc none /proc
>>    # mount -t sysfs none /sys
>>    # mount /dev/sda8 /boot  (if using a separate boot partition)
>>
>>  9) Set root password
>>
>>    # passwd
>>
>>  10) Make an acount
>>
>>    # groupadd -g 1000 <my-user-name>
>>    # useradd -g <my-user-name> -u 1000 -c "My Name" -s /bin/bash
>> <my-user-name>
>>    # passwd <my-user-name>
>>
>>  11) Edit /nilfs/etc/apt/sources.list
>>
>>  12) Set timezone
>>
>>    # dpkg-reconfigure tzdata
>>
>>  13) Install packages
>>
>>    # apt-get update
>>    # apt-get install rsync ssh openssh-server sudo gcc make git-core
>>      automake autoconf aptitude ...
>>
>>  14) Build and install nilfs-utils
>>
>>  15) Manually build and install util-linux-ng which supports nilfs2.
>>      This is required to mount nilfs2 partitions by a UUID or a LABEL.
>>
>>  16) Install and setup grub2, and run update-grub program
>>
>>  17) Reboot
>>
>>  18) Install desktop environment
>>
>>
>> I think this needs trial and error for natty since this memorandum was
>> originally made for Debian.
>>
>>
>> Regards,
>> Ryusuke Konishi
>>
>>> I know these are not dev-related questions, but I'm planning on writing
>>> several nilfs2-related tutorials, and need to know exactly how a disk
>>> should be partitioned for it.
>>>
>>> Thanks,
>>>
>>>
>>> --
>>> Fini D.
>>>
>>>
>>>
>>> > Hi,
>>> > On Mon, 4 Jul 2011 13:28:39 -0600, "LinuxBSDos.com" wrote:
>>> >>
>>> >> Hi,
>>> >>
>>> >> A couple of Linux distributions now have nilfs2 as an optional file
>>> >> system
>>> >> during installation and I just want to find out what the minimum
>>> number
>>> >> of
>>> >> partitions required for a nilfs2-based installation is.
>>> >>
>>> >> Is it necessary to create separate partitions for the major file
>>> >> systems,
>>> >> or does nilfs2 require just one root file system directory? Is /home
>>> on
>>> >> a
>>> >> separate partition necessary?
>>> >
>>> > nilfs2 can be used as a root filesystem and it is bootable from
>>> recent
>>> > grub2.  I'm using nilfs2 for the root filesystem on my ubuntu-natty
>>> > laptop.
>>> >
>>> > One restriction is that nilfs2 does not support swap file, so users
>>> > need at least two partitions, swap and root.
>>> >
>>> > /home is not necessary to be a separate partition.
>>> >
>>> >> Lastly, can I encrypt a nilfs2 partition?
>>> >
>>> > nilfs2 itself does not support encryption.  Instead, it can be used
>>> > together with ecryptfs or dm-crypt.
>>> >
>>> > Thanks,
>>> > Ryusuke Konishi
>>> >
>>> >> Thanks,
>>> >>
>>> >> --
>>> >> Fini D.
>>> >>
>>> >> --
>>> >> To unsubscribe from this list: send the line "unsubscribe
>>> linux-nilfs"
>>> >> in
>>> >> the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
>>> >> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>>> > --
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>>> linux-nilfs"
>>> in
>>> > the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
>>> > More majordomo info at  http://vger.kernel.org/majordomo-info.html
>>> >
>>>
>>>
>>> --
>>> To unsubscribe from this list: send the line "unsubscribe linux-nilfs"
>>> in
>>> the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
>>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>> --
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>> in
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>>
>
>
> --
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Re: Recommended partition scheme for nilfs2

[dexen deVries]

On Wednesday 06 July 2011 18:05:29 you wrote:
> Just one more thing.
> 
> For btrfs and other file systems, it is customary to have a separate boot
> partition, so that at a minimum, you have 3 partitions - /boot, Swap, and
> /. Would that be a problem for nilfs2?
> 
> If it is ok to have a separate boot partition, does it make sense to use
> nilfs2 on it? Or is it better to use a non-journaling file system, like
> Linux Native (ext2) on the boot partition, and nilfs2 on /.


for reference, my setup at home and at work:
two harddrives, one for / and /boot, the other for /home.

both / and /home are NILFS2, while /boot is ext3.

i wanted a very reliable journaling FS on /boot to lessen risk of foobar, and 
also I'm using lilo, which is not supported by NILFS2 yet -- lack of fibmap 
syscall.


-- 
dexen deVries

> (...) I never use more than 800Mb of RAM. I am running Linux,
> a browser and a terminal.
rjbond3rd in http://news.ycombinator.com/item?id=2692529
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Re: Recommended partition scheme for nilfs2

[Ryusuke Konishi]

On Wed, 6 Jul 2011 19:19:37 +0200, dexen deVries wrote:
> On Wednesday 06 July 2011 18:05:29 you wrote:
> > Just one more thing.
> > 
> > For btrfs and other file systems, it is customary to have a separate boot
> > partition, so that at a minimum, you have 3 partitions - /boot, Swap, and
> > /. Would that be a problem for nilfs2?
> > 
> > If it is ok to have a separate boot partition, does it make sense to use
> > nilfs2 on it? Or is it better to use a non-journaling file system, like
> > Linux Native (ext2) on the boot partition, and nilfs2 on /.
> 
> 
> for reference, my setup at home and at work:
> two harddrives, one for / and /boot, the other for /home.
> 
> both / and /home are NILFS2, while /boot is ext3.
> 
> i wanted a very reliable journaling FS on /boot to lessen risk of
> foobar,

As dexen mentioned, separating boot partition is more reliable.  And I
think ext3 is a good choice for it.  This configuration is recommended
especially if you make a dual boot environment.

On the other hand, incorporating /boot into / is not bad choice if
grub2 and initramfs-tools are properly set up and used.  This
configuration is simple and allows us to back up a fully consistent
state of the system (with a snapshot).

> and also I'm using lilo, which is not supported by NILFS2 yet --
> lack of fibmap syscall.

This topic was once discussed with the title of "FIBMAP ioctl
missing".

fibmap internally uses bmap vfs method.  Adding the feature is not so
difficult, but it must not be used for overwriting data blocks because
nilfs everytime changes allocation of file blocks due to its COW
nature.  Garbage collection also blows up safety of such operation.
Unfortunately, swap file is actually doing it.

Does LILO use fibmap for read-only purpose ?

If so, we only need a method to deny direct block write by the swap
file.


Regards,
Ryusuke Konishi
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Re: Recommended partition scheme for nilfs2

[LinuxBSDos.com]

Thank you.

> On Wednesday 06 July 2011 18:05:29 you wrote:
>> Just one more thing.
>>
>> For btrfs and other file systems, it is customary to have a separate
>> boot
>> partition, so that at a minimum, you have 3 partitions - /boot, Swap,
>> and
>> /. Would that be a problem for nilfs2?
>>
>> If it is ok to have a separate boot partition, does it make sense to use
>> nilfs2 on it? Or is it better to use a non-journaling file system, like
>> Linux Native (ext2) on the boot partition, and nilfs2 on /.
>
>
> for reference, my setup at home and at work:
> two harddrives, one for / and /boot, the other for /home.
>
> both / and /home are NILFS2, while /boot is ext3.
>
> i wanted a very reliable journaling FS on /boot to lessen risk of foobar,
> and
> also I'm using lilo, which is not supported by NILFS2 yet -- lack of
> fibmap
> syscall.
>
>
> --
> dexen deVries
>
>> (...) I never use more than 800Mb of RAM. I am running Linux,
>> a browser and a terminal.
> rjbond3rd in http://news.ycombinator.com/item?id=2692529
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Re: Recommended partition scheme for nilfs2

[LinuxBSDos.com]

Thanks for taking the time to answer my questions.

> On Wed, 6 Jul 2011 19:19:37 +0200, dexen deVries wrote:
>> On Wednesday 06 July 2011 18:05:29 you wrote:
>> > Just one more thing.
>> >
>> > For btrfs and other file systems, it is customary to have a separate
>> boot
>> > partition, so that at a minimum, you have 3 partitions - /boot, Swap,
>> and
>> > /. Would that be a problem for nilfs2?
>> >
>> > If it is ok to have a separate boot partition, does it make sense to
>> use
>> > nilfs2 on it? Or is it better to use a non-journaling file system,
>> like
>> > Linux Native (ext2) on the boot partition, and nilfs2 on /.
>>
>>
>> for reference, my setup at home and at work:
>> two harddrives, one for / and /boot, the other for /home.
>>
>> both / and /home are NILFS2, while /boot is ext3.
>>
>> i wanted a very reliable journaling FS on /boot to lessen risk of
>> foobar,
>
> As dexen mentioned, separating boot partition is more reliable.  And I
> think ext3 is a good choice for it.  This configuration is recommended
> especially if you make a dual boot environment.
>
> On the other hand, incorporating /boot into / is not bad choice if
> grub2 and initramfs-tools are properly set up and used.  This
> configuration is simple and allows us to back up a fully consistent
> state of the system (with a snapshot).
>
>> and also I'm using lilo, which is not supported by NILFS2 yet --
>> lack of fibmap syscall.
>
> This topic was once discussed with the title of "FIBMAP ioctl
> missing".
>
> fibmap internally uses bmap vfs method.  Adding the feature is not so
> difficult, but it must not be used for overwriting data blocks because
> nilfs everytime changes allocation of file blocks due to its COW
> nature.  Garbage collection also blows up safety of such operation.
> Unfortunately, swap file is actually doing it.
>
> Does LILO use fibmap for read-only purpose ?
>
> If so, we only need a method to deny direct block write by the swap
> file.
>
>
> Regards,
> Ryusuke Konishi
> --
> To unsubscribe from this list: send the line "unsubscribe linux-nilfs" in
> the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
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Re: Recommended partition scheme for nilfs2

[Ryusuke Konishi]

On Thu, 07 Jul 2011 12:21:42 +0900 (JST), Ryusuke Konishi wrote:
> On Wed, 6 Jul 2011 19:19:37 +0200, dexen deVries wrote:
> > On Wednesday 06 July 2011 18:05:29 you wrote:
> > and also I'm using lilo, which is not supported by NILFS2 yet --
> > lack of fibmap syscall.
> 
> This topic was once discussed with the title of "FIBMAP ioctl
> missing".
> 
> fibmap internally uses bmap vfs method.  Adding the feature is not so
> difficult, but it must not be used for overwriting data blocks because
> nilfs everytime changes allocation of file blocks due to its COW
> nature.  Garbage collection also blows up safety of such operation.
> Unfortunately, swap file is actually doing it.
> 
> Does LILO use fibmap for read-only purpose ?
> 
> If so, we only need a method to deny direct block write by the swap
> file.

That was not enough.  I guess LILO uses block mapping assuming it's
pinned to the place.  It's not easy to implement within nilfs.

Ryusuke Konishi
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Re: Recommended partition scheme for nilfs2

[dexen deVries]

On Thursday 07 of July 2011 06:04:23 you wrote: 
> > This topic was once discussed with the title of "FIBMAP ioctl
> > missing".
> > 
> > fibmap internally uses bmap vfs method.  Adding the feature is not so
> > difficult, but it must not be used for overwriting data blocks because
> > nilfs everytime changes allocation of file blocks due to its COW
> > nature.  Garbage collection also blows up safety of such operation.
> > Unfortunately, swap file is actually doing it.
> > 
> > Does LILO use fibmap for read-only purpose ?
> > 
> > If so, we only need a method to deny direct block write by the swap
> > file.
> 
> That was not enough.  I guess LILO uses block mapping assuming it's
> pinned to the place.  It's not easy to implement within nilfs.

That's my understanding as well. LILO, upon `installation' (the `lilo' command) creates a static map of which blocks make up kernel file (and optionally initial ramdisk). Basically we'd have to ensure the kernel file blocks are never moved around, which'd increase complexity of NILFS2. Leaving 128MB /boot partition gets the job done at benign cost.

FWIW, I got fingers burned by grub's complexity a few times, so I stick to the simple LILO.

Btw., Ryusuke, you've mentioned that blocks being part of a snapshot are never moved  around, right? If that's the case, keeping kernel files on snapshot would be enough, but snapshots can be deleted (and subsequently GC'd) at any time.

We could hack around that in a somewhat standard way with `chattr +i /boot/vmlinuz-xxx', provided NILFS2 supported the `i' (immutable) attribute (as discussed in man chattr(1)), but again that's some complexity. Or +t which was meant to secure against tail-merging for use with LILO.


-- 
dexen deVries

[[[↓][→]]]

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   <?kzy irefvba="1.0" rapbqvat="ebg13"?>
an XML parser will recognize that the document is stored in the traditional ROT13 encoding.

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Re: Recommended partition scheme for nilfs2

[Ryusuke Konishi]

Hi,
On Thu, 7 Jul 2011 11:13:48 +0200, dexen deVries wrote:
> On Thursday 07 of July 2011 06:04:23 you wrote: 
> > > This topic was once discussed with the title of "FIBMAP ioctl
> > > missing".
> > > 
> > > fibmap internally uses bmap vfs method.  Adding the feature is not so
> > > difficult, but it must not be used for overwriting data blocks because
> > > nilfs everytime changes allocation of file blocks due to its COW
> > > nature.  Garbage collection also blows up safety of such operation.
> > > Unfortunately, swap file is actually doing it.
> > > 
> > > Does LILO use fibmap for read-only purpose ?
> > > 
> > > If so, we only need a method to deny direct block write by the swap
> > > file.
> > 
> > That was not enough.  I guess LILO uses block mapping assuming it's
> > pinned to the place.  It's not easy to implement within nilfs.
> 
> That's my understanding as well. LILO, upon `installation' (the
> `lilo' command) creates a static map of which blocks make up kernel
> file (and optionally initial ramdisk). Basically we'd have to ensure
> the kernel file blocks are never moved around, which'd increase
> complexity of NILFS2. Leaving 128MB /boot partition gets the job
> done at benign cost.
> 
> FWIW, I got fingers burned by grub's complexity a few times, so I
> stick to the simple LILO.
> 
> Btw., Ryusuke, you've mentioned that blocks being part of a snapshot
> are never moved around, right? If that's the case, keeping kernel
> files on snapshot would be enough, but snapshots can be deleted (and
> subsequently GC'd) at any time.

No, blocks held by snapshots are moved by GC.  Recall how GC reclaims
segments (watch output of lssu command continually).

To pin specified data blocks, we need to introduce "immutable segment"
which is never selected for garbage collection, or need to add
"imovable flag" for such files.  Both are not present in the current
nilfs.

> We could hack around that in a somewhat standard way with `chattr +i
> /boot/vmlinuz-xxx', provided NILFS2 supported the `i' (immutable)
> attribute (as discussed in man chattr(1)), but again that's some
> complexity. Or +t which was meant to secure against tail-merging for
> use with LILO.

The current nilfs supports the immutable flag, but yes, the immutable
attribute does not imply the file is immovable on disk.  We need a new
flag for that.. though I don't like adding such own attribute.


Regards,
Ryusuke Konishi
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