wiped disk - no longer bootable

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Re: wiped disk - no longer bootable

Liam Proven
On Mon, 15 Jul 2019 at 12:48, compdoc <[hidden email]> wrote:

> I don't use it either, which is why I don't know a lot about it. Way
> back when, lots of utilities that I used to repair system wouldn't work
> with it.

True.

> However, many have used LVM and encryption successfully for years, and
> the Ubuntu installer defaults to it for encryption. And lots of
> utilities will work with it now. Therefore, I have to declare it safe
> and sound

Oh, yes, I think it is. Overcomplex and difficult, but safe, sure.

The thing is,  if you only have 1 or even 2 disks, it really doesn't
give you anything useful.

Therefore, I can't agree with:

> and a reasonable choice.

I think that only applies if you're juggling enough drives to make not
just RAID viable, but RAID 6 or above.

RAID 0 (striping) and RAID 1 (mirroring) aren't true RAID. RAID 5 is
minimum 3 disks. RAID 6 is 2 parity disks -- an array can lose 2
drives and keep running -- and only works with 4+ drives. It's only
really worth doing with 5+ drives.

Which is where stuff starts to get complex. It needs effort to plan
and to implement.

If you are into that zone of complexity, then LVM pays back the effort.

OTOH, I would prefer something that integrates LVM into partitioning
and formatting. Such as XFS, or Stratis when it becomes stable and
mature enough.

There *was* something like that, called EVMS:

https://en.wikipedia.org/wiki/Enterprise_Volume_Management_System

But LVM was simpler at implementation level, so EVMS never made it
into the kernel. The EVMS team gracefully backed down.

The problem is that sometimes the thing that is simpler to implement
is more complex to use. This is called the "worse is better" approach
and all of *nix is a direct result of it:

https://www.jwz.org/doc/worse-is-better.html

> Its the using of a 500Gig drive as
> cache that's stupid when SSDs are so fast and reliable, and OSes and
> programs will cache intelligently for you these days.

Agreed. I would not use a word so strong as "stupid" but I don't see the point.

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Re: wiped disk - no longer bootable

Volker Wysk
In reply to this post by Liam Proven

Zitat von Liam Proven <[hidden email]>:

> On Sat, 13 Jul 2019 at 15:57, Volker Wysk <[hidden email]> wrote:
>
>> "beyond the skills and/or imagination of those trying to help you."
>> denotes my SSD-as-a-Cache, isn't it?
>
> Not *just* that, no.
>
> LVM + encryption + ssd-as-cache = fear
>
> * I don't like LVM and don't use it. It makes life too complex. IMHO
> it is only worth it on big servers with multiple hard disks.
>
> (I speak as someone who has made a career out of understanding and
> mastering difficult IT technology since the 1980s. I can judge when
> something is elegant and when it's a nasty kludge. In my professional
> opinion, LVM is a nasty kludge. It has too many layers: a partitioning
> scheme, then LVM, then partitions on LVM, then a filesystem on the
> partitions. That is nasty. This is why more modern filesystems such as
> ZFS *exist*: they merge the volume management and partitioning and
> filesystem into one layer. This removes a lot of duplication and makes
> them easier to understand, to implement, and in theory, more robust.
> Btrfs does some of this but IMHO not enough. Even Red Hat has
> acknowledged this and as a result it is developing its own new volume
> manager, Stratis, which merges LVM and XFS into one unit.)

Maybe it's because I don't know anything different, but I don't feel  
like it's that complicated. Especially if you don't dig into it, but  
just use the Ubuntu installer.  ;-)

> * I don't like disk encryption and don't use it.
>
> (E.g. at my previous job at a Linux vendor, I was issued a very nice-
> then state-of-the-art Thinkpad X240 with a ½ TB SSD. But company rules
> meant it had to have full disk encryption (FDE). It took me 3 days to
> get this working -- that's after ½ century of Linux knowledge, and,
> you know, _getting a job at a Linux vendor_ -- and when it worked the
> machine became as slow as if it had a hard disk.)

So you manually set up full disk encryption, because you had to. For  
me it's the same as above: Just use the Ubuntu installer. No stress.

> FDE is arguably worth it if *both* [a] you work with confidential info
> and [b] you use a notebook which could be lost or stolen. On a desktop
> or on a home computer, forget it.

There are many possible circumstances which make you want encryption...

> * SSD as cache: why?
>
> The easy way is root on SSD, /home on HD. This gives great speed for
> most jobs and can be tuned with tools such as compcache, tmpfs,
> swapspace, zram and so on to ensure that temporary work files are held
> on nice fast media while you have a dead simple, easy-to-troubleshoot
> disk setup.

You just caught me on giving up on SSD-as-a-cache. I've tried to set  
it up again, but it doesn't work. It possibly comes from incompatible  
changes in the OS (Kubuntu 18.04 versus Ubuntu 19.04).

I spent a lot of time earlier, on setting it up. Time which I don't  
want to go to waste. But I don't want to go into the details again,  
either. And when I manage to get it working again, for how long will  
that be?

So I will do something as / on SSD and /home on HDD. But I have a lot  
of pictures. It's much faster when they reside an on SSD, or a HDD  
with SSD-as-a-cache. I will have to make a setup with user files  
partially on the SSD. Using a lot of symlinks.

Cheers,
Volker


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Re: Filesystem corruption

Volker Wysk
In reply to this post by Liam Proven
Zitat von Liam Proven <[hidden email]>:
> On Thu, 11 Jul 2019 at 20:56, Volker Wysk <[hidden email]> wrote:

>> Thanks for your explaination. It means that I will probably stick with
>> LTS versions.
>
> You're welcome. LTS releases do make for a quieter life. :-)
>
> You can always dual-boot the current release as a standby and if you
> want to experiment.

What exactly does "dual-boot" mean? Having two different systems, with  
/home on a separate partition, with it being mounted by either, when  
running?

V.


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Re: Filesystem corruption

Oliver Grawert
hi,
Am Dienstag, den 16.07.2019, 17:21 +0200 schrieb Volker Wysk:

> Zitat von Liam Proven <[hidden email]>:
> >
> > On Thu, 11 Jul 2019 at 20:56, Volker Wysk <[hidden email]>
> > wrote:
> >
> > >
> > > Thanks for your explaination. It means that I will probably stick
> > > with
> > > LTS versions.
> > You're welcome. LTS releases do make for a quieter life. :-)
> >
> > You can always dual-boot the current release as a standby and if
> > you
> > want to experiment.
> What exactly does "dual-boot" mean? Having two different systems,
> with  
> /home on a separate partition, with it being mounted by either,
> when  
> running?
>
simply booting two different OSes (or two different versions of the
same OS) while picking between them on boot

*NEVER EVER* !!! share your home between two OSes or different releases
... the way an application stores data, passwords or configs might be
completely different between the two versions on the different
releases/OSes, formats might have changed etc. this will likely cause
corruption and/or application breakage.

ciao
        oli
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Re: Filesystem corruption

eric avendaño cruz
Deseo salir del grupo como puedo hacerlo?
De: ubuntu-users <[hidden email]> en nombre de Oliver Grawert <[hidden email]>
Enviado: martes, 16 de julio de 2019 10:49:21 a. m.
Para: [hidden email]
Asunto: Re: Filesystem corruption
 
hi,
Am Dienstag, den 16.07.2019, 17:21 +0200 schrieb Volker Wysk:
> Zitat von Liam Proven <[hidden email]>:
> >
> > On Thu, 11 Jul 2019 at 20:56, Volker Wysk <[hidden email]>
> > wrote:
> >
> > >
> > > Thanks for your explaination. It means that I will probably stick
> > > with
> > > LTS versions.
> > You're welcome. LTS releases do make for a quieter life. :-)
> >
> > You can always dual-boot the current release as a standby and if
> > you
> > want to experiment.
> What exactly does "dual-boot" mean? Having two different systems,
> with  
> /home on a separate partition, with it being mounted by either,
> when  
> running?
>

simply booting two different OSes (or two different versions of the
same OS) while picking between them on boot

*NEVER EVER* !!! share your home between two OSes or different releases
... the way an application stores data, passwords or configs might be
completely different between the two versions on the different
releases/OSes, formats might have changed etc. this will likely cause
corruption and/or application breakage.

ciao
        oli

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Re: Filesystem corruption

Volker Wysk
In reply to this post by Oliver Grawert
Zitat von Oliver Grawert <[hidden email]>:

> hi,
> Am Dienstag, den 16.07.2019, 17:21 +0200 schrieb Volker Wysk:
>> Zitat von Liam Proven <[hidden email]>:
>> >
>> > On Thu, 11 Jul 2019 at 20:56, Volker Wysk <[hidden email]>
>> > wrote:
>> >
>> > >
>> > > Thanks for your explaination. It means that I will probably stick
>> > > with
>> > > LTS versions.
>> > You're welcome. LTS releases do make for a quieter life. :-)
>> >
>> > You can always dual-boot the current release as a standby and if
>> > you
>> > want to experiment.
>> What exactly does "dual-boot" mean? Having two different systems,
>> with  
>> /home on a separate partition, with it being mounted by either,
>> when  
>> running?
>>
>
> simply booting two different OSes (or two different versions of the
> same OS) while picking between them on boot
>
> *NEVER EVER* !!! share your home between two OSes or different releases
> ... the way an application stores data, passwords or configs might be
> completely different between the two versions on the different
> releases/OSes, formats might have changed etc. this will likely cause
> corruption and/or application breakage.

Okay. Good thing you pointed it out.

V.W.


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Re: Filesystem corruption

C de-Avillez-2
In reply to this post by eric avendaño cruz
On Tue, Jul 16, 2019 at 4:03 PM eric avendaño cruz <[hidden email]> wrote:
>
> Deseo salir del grupo como puedo hacerlo?

Sorry, can read Spanish, pero no hablo. So, there it goes:

At the bottom of *every* email sent thru the mailing list you have:

"ubuntu-users mailing list
[hidden email]
Modify settings or unsubscribe at:
https://lists.ubuntu.com/mailman/listinfo/ubuntu-users"
                             ^^^^^^^

Cheers,

..C..

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Re: Filesystem corruption

Liam Proven
In reply to this post by Volker Wysk
On Tue, 16 Jul 2019 at 17:23, Volker Wysk <[hidden email]> wrote:
>
> What exactly does "dual-boot" mean? Having two different systems, with
> /home on a separate partition, with it being mounted by either, when
> running?

The shared /home is optional . Just 2 OSes side by side in their own
partitions. That's all it means.


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Re: Filesystem corruption

Liam Proven
In reply to this post by Oliver Grawert
On Tue, 16 Jul 2019 at 17:51, Oliver Grawert <[hidden email]> wrote:

> *NEVER EVER* !!! share your home between two OSes or different releases
> ... the way an application stores data, passwords or configs might be
> completely different between the two versions on the different
> releases/OSes, formats might have changed etc. this will likely cause
> corruption and/or application breakage.

We've argued over this before.

Your claim is wrong. This is not correct.

[1] If you use a different username it is 100% guaranteed safe. That's
all it takes.

[2] Even if you use the same username, so long as it is the only user
account on both/all the Linuxes, it will usually work fine. I have
done this, repeatedly. It works.

However, yes, option #1 is easier and safer.

You keep saying it *will* fail and *will* break. This is not the case.
There _can_ be problems but it does work. I know because I have done
it, myself, personally.

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Re: Filesystem corruption

Liam Proven
In reply to this post by eric avendaño cruz
On Tue, 16 Jul 2019 at 18:05, eric avendaño cruz <[hidden email]> wrote:
>
> Deseo salir del grupo como puedo hacerlo?

This is an English language group.

Please bottom quote.

If you want to leave, instructions are in the signature on every
message you get.

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