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Re: best practice for lvm?



In <[🔎] 20090603185138.GA25966@m364d1.ece.northwestern.edu>, Zhengquan Zhang 
wrote:
>On Wed, Jun 03, 2009 at 01:46:27PM -0500, Boyd Stephen Smith Jr. wrote:
>> In <[🔎] 20090603174408.GA25275@m364d1.ece.northwestern.edu>, Zhengquan Zhang
>>
>> wrote:
>> >Can I say the best practice for lvm is to create a single partition for
>> >the harddrive and single PV on it
>>
>> I prefer not to use a partition table at all if I'm using the whole disk
>> for LVM.
>
>I just read this from the lvm howto
>
>http://tldp.org/HOWTO/LVM-HOWTO/initdisks.html
>
>Not Recommended
>
>Using the whole disk as a PV (as opposed to a partition spanning the
>whole disk) is not recommended because of the management issues it can
>create. Any other OS that looks at the disk will not recognize the LVM
>metadata and display the disk as being free, so it is likely it will be
>overwritten. LVM itself will work fine with whole disk PVs.

This doesn't really apply to me, as I refuse to run MS Windows on my own 
hardware and haven't had occasion to use BSD/Hurd/Mac OS X/OpenSolaris.

>could you explain why it is good to use whole disk for lvm?

From what I understand, you might get one extra PE.  But, that's all I can 
think of.  There's no performance change.

Maybe having a partition table is better, but I don't understand the desire 
for a partition table when it is not really going to the used to partition 
(i.e. divide into parts) the disk.

>> >and separate LVs for /tmp /var /home
>>
>> You definitely want separate LVs for any partition (non-system) users
>> can write to, to avoid running out of space on your / partition.  I
>> usually go overboard and have separate partitions for:
>> /boot      # If / is on LVM; not LV
>> /usr
>> /usr/local # For OS migrations.
>
>Could you elaborate on this, I'd really like to learn more about your
>setup. Do you put OS independent stuff in this?

Right now, the only thing I have in there is 
/usr/local/share/doc/susv{1,2,3}.  It's documentation I want available to 
any user on the system, but that isn't provided by openSUSE.  In the past I 
also put extra xessions in /usr/local/share/xessions and local scripts or 
programs in /usr/local/{s,}bin.

Basically, it is for replacements/extensions/additions to /usr.  I reserve 
/usr to the OS package manager.

This allows be to reformat/delete the contents of /usr -- for migrating from 
openSUSE to Debian or vice-versa.

>> /home
>> /opt
>> /srv
>> /var
>> /var/tmp   # RAID 0 or other "fast"
>> /var/cache # RAID 0 or other "fast"
>> /tmp       # Usually tmpfs; no LV
>
>This setup is intense.

Yeah, as I said, it might be overkill.  For my VPSes I just use the setup my 
provider gave me; one large partition for / and one small partition for 
swap.  For my laptop, I'm using small partition for /boot, large parititon 
for LV.  LVs for /, /usr/local, /home, and swap. /tmp on tmpfs.  My desktop 
is the only system that has the "full" layout.

If you have 2G or more of RAM, you will most likely be fine having /tmp on 
tmpfs.  You can probably do it on even less RAM.
-- 
Boyd Stephen Smith Jr.           	 ,= ,-_-. =.
bss@iguanasuicide.net            	((_/)o o(\_))
ICQ: 514984 YM/AIM: DaTwinkDaddy 	 `-'(. .)`-'
http://iguanasuicide.net/        	     \_/

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