A logical volume will not extend beyond its allocated size, even if there is
free space in the volume group. You can choose to expand it, but it will
take a specific set of actions; it won't be automatic.
--
.~. Robert P. Nix Mayo Foundation
/V\ RO-OC-1-13 200 First Street SW
/( )\ 507-284-0844 Rochester, MN 55905
^^-^^ -----
"In theory, theory and practice are the same, but
in practice, theory and practice are different."
On 3/22/07 12:53 PM, "Ayer, Paul W" <[EMAIL PROTECTED]> wrote:
> * With /var now set to 3.00 GB does this allow /var to ONLY get as big
> as
> 3.00 GB and stop? OR would should each mount point be in it's own vol
>
> Group to achieve that?
>
>
> -----Original Message-----
> From: Linux on 390 Port [mailto:[EMAIL PROTECTED] On Behalf Of
> RPN01
> Sent: Thursday, March 22, 2007 12:01 PM
> To: [email protected]
> Subject: Re: can a max file size be set when using lvm
>
> The problem with a layout like this is the granularity. With the root
> being
> one large filesystem, and containing lots of other directories, you
> leave
> yourself open to possible failures that can be avoided if you use LVM
> and
> break up this filesystem.
>
> The /var and /tmp directories can consume space very quickly, leaving
> you
> with a root filesystem that is completely full without much notice. If
> these
> are broken off into their own filesystems, they're much more controlled,
> and
> can be more easily watched and problems diagnosed quicker.
>
> The /home filesystem has the same problem as the other two; A runaway
> task
> owned by some user can fill the filesystem quickly, leaving you...
> Surprised.
>
> Another problem comes if the guest needs to be re-imaged. Having /home
> in
> with the root filesystem means that you can't just scratch that
> filesystem
> and start over. You have to spend time moving data out, and then later
> back
> in.
>
> While you can allocate several smaller minidisks via zVM, you have to be
> able to maintain the structure. It's somewhat of a problem to expand a
> minidisk, while LVM allocations can be expanded and contracted very
> quickly,
> and additional minidisks can be added to the volume group to address
> future
> needs.
>
> Our current standard is to allocate two 3390 mod 9 equivalent minidisks
> to a
> new guest. The first becomes volume group vg_system, and is broken down
> into
> /tmp (500 mb), /var (2.5 gb), swap (1 gb) and the root directory
> (whatever's
> left). The second mod 9 becomes vg_local, and has /home (2 gb) and /opt
> (5.4
> gb). We have most of our non-distribution software installed in the /opt
> path.
>
> If we need to move the users to another guest, we can move the second
> mod 9
> to the other system, and they'd still have all their data and
> applications.
> If the users run out of room, it's fairly simple to add another volume
> to
> the volume group and expand the directory needing space. It's also
> fairly
> easy to create another logical volume in the group and add another path
> and
> filesystem when needed.
>
> We haven't really seen any crashes due to root being in LVM. Where we
> have
> had trouble, we'd have had the same problem with a flat filesystem as
> well.
> Logging in twice comes to mind...
>
> Note too that we set up our Intel-based Linux boxes in much the same
> way. In
> this way, we can walk up to any "box" and have some reasonable
> expectations.
>
> On logrotate: This tool does a great job... For what it works with. An
> example where if fails to fit is sar data and reports, which already
> have a
> timestamp in the name. logrotate doesn't handle files in that format, so
> you
> end up having to come up with another way to control them. The rmf
> collector
> is another one that has this problem, except in the /opt path. Printing
> and
> e-mail can fill /var if there is some problem with a task creating files
> in
> these spaces. /var can still fill up, despite your best efforts to
> control
> it.
>
> This layout has worked very well for us... Your mileage may vary.
>
>
> --
> .~. Robert P. Nix Mayo Foundation
> /V\ RO-OC-1-13 200 First Street SW
> /( )\ 507-284-0844 Rochester, MN 55905
> ^^-^^ -----
> "In theory, theory and practice are the same, but
> in practice, theory and practice are different."
>
>
>
>
> On 3/22/07 10:16 AM, "Michael MacIsaac" <[EMAIL PROTECTED]> wrote:
>
>>> If in the install I set say 10 2.3g disks into one lvm
>>> Setting the Mount point to /
>>
>> Others have described issues when using a logical volume for the root
> file
>> system. If LVM gets confused, which happens from time to time, then
> your
>> system doesn't boot. I would recommend keeping the root file system on
> a
>> conventional mindisk/DASD.
>>
>> -Maybe- you only want to use LVM when you have to. Suppose the base
>> system is three 3390-3s - one for /, one for /usr and one for /opt
> let's
>> say (or put / on a single 3390-9). If a minimal system is about 1GB
> (see
>> below), then your base system / is perhaps 17% used, /usr is 28% used
> and
>> /opt is pretty much empty. There's a fair amount of room for growth:
>>
> <snip>
>>
>> Then if you need to put a large chuck of data somewhere, you create an
> LVM
>> and mount it where it is needed.
>>
>> I feel the whole possible issue of "the root file system will fill up"
> is
>> overblown. logrotate does its job. Just my two cents - I sure others
> will
>> have different suggestions.
>>
>> "Mike MacIsaac" <[EMAIL PROTECTED]> (845) 433-7061
>>
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