Booting - Enterprise Volume Management System

[Alexander Skwar]

Toby Kelsey <toby_kelsey at ntlworld.com>:
> Alexander Skwar wrote:
>> Toby Kelsey <toby_kelsey at ntlworld.com>:

>>>Interesting.  Looking at the HOWTO, it seems that LVM combines the main 
>>>disadvantage of separate partitions - having to manually unmount and resize when 
>>>you run out of space
>> 
>> 
>> unmount? Have you actually read the howto?
> 
> Perhaps you should try reading it.

Same to you. But perhaps, you should get some experience.

> "  ext2/ext3
> 
> Unless you have patched your kernel with the ext2online patch it is necessary to 
> unmount the file system before resizing it."

As I said, ext3 can be resized online, as far as I know. I've also
said, that I don't use ext3. 

> Reiserfs, xfs and jfs can be grown mounted, but reiserfs is slower and allegedly 
> buggier than other filesystems, and xfs and jfs are unsuitable for LVM as I have 
> mentioned already.

In how far are XFS and JFS unsuitable? Because they can't be made
smaller?

If so, then they are also unsuitable for old fashioned partitioning, by
what you say.

>>>- with the main disadvantage of one big partition -  
>>>allowing fs corruption and installers to affect user and system data together. 
>> 
>> 
>> What are you talking about?
> 
> You don't think there are any disadvantages of one big partition?

Yes, of course I do think so. Reason: You can't make specialized
filesystems.

But I don't see a disadvantage in having one huge partition. I see
a disadvantage in having one huge filesystem which spans the whole
disk.

What kind of disadvantage should there be, if there's just one huge
partition?

> Why even  
> bother with LVM on a single disk if you can just make one big partition?

To have multiple file systems.

Why make just one big partition?

>>>The main advantage appears being able to resize logical volumes and filesystems 
>>>easily, but for jfs "this is extremely error prone"
>> 
>> 
>> How so? mount -o remount,resize /your/jfs
> 
> Perhas you know better than the HOWTO:

I don't. I just know, that it works very well.

> "Known Kernel Bug
> 
> Some kernel versions have problems with this syntax (2.6.0 is known to have this 
> problem).

This is *VERY* old. The current kernel is 2.6.17.7. Ubuntu ships 2.6.15.

> Until "some kernels" are identified or fixed it is not safe.  I am not going to 
> continue pasting blocks of text from the HOWTO every time you profess ignorance. 
>   Please read it.

Same to you.

>>>and even for ext2/3 "there  
>>>is currently no e2fsadm equivalent for LVM 2
>> 
>> 
>> True, but ext3 can be made larger online, AFAIK. I don't use ext3, though.
> 
> With a kernel patch which is judged "rather dangereous" as I already said.
> If you only use reiserfs anyway then LVM is more useful.

I also use xfs and jfs and LVM is very useful. It's also useful with ext3.

>>>Since you cannot shrink xfs and jfs the main functionality becomes  
>>>useless for many advanced users.
>> 
>> 
>> Wrong. Mostly, filesystems will grow. It's, in my experience, quite
>> rare, that filesystems need to be made smaller.
> 
> You can grow and move partitions with parted anyway,

Oh, you can do that online? You don't have to take down close to everything?
Since when does the kernel directly, ie. with no reboot, take notice of
the new partition boundaries?

> so LVM has no advantage if  
> that's what you restrict it to.

"that" == to what? making bigger?

You're wrong.

Suppose you've got hda5 up to hda10. Now you need to make hda5 bigger.

Much fun!

Or can this be done WITHOUT taking hda5, hda6, hda7, hda8, hda9 and hda10
"offline" (ie. unmounting the file systems contained on those partitions)?
I honestly don't know that, but from what you say, it sounds as if this
is possible. Do you have proof for that?

> Of course you can also use LVM with multiple  
> disks, and it has a genuine advantage there.  I suspect it is not as fast as 
> using specific software or hardware RAID though,

LVM isn't some sort of "RAID". That's what RAID is for. Actually, it's not
unusual to use (Software-)RAID and LVM in combination.

>>>While it may be useful for servers, with confidence-building statements like "it 
>>>seems that the online resizing patch is rather dangerous" I would suggest it is 
>>>not yet suitable for a home or laptop system.
>> 
>> 
>> Wrong. On what experience do you base your conclusion? On your false reading?
> 
> Based on the HOWTO.  Please read it.

So, you base this on *no* experience?

> LVM has its place if you know what you are doing (and have multiple disks with 
> partitions which grow and never shrink),

And also, if you have just one disk.

> but the "LVM is good for everybody,  
> even laptop users" rhetoric 

Which is completely right.

> I responded to was OTT. 

OTT?

Alexander Skwar
-- 
Keep the phase, baby.