Thanks Peter! I think this will be a great compliment to Lustre's
existing feature set.
- Sridhar
________________________________
From: Peter Braam [mailto:[EMAIL PROTECTED]
Sent: Tuesday, January 09, 2007 5:45 PM
To: Lin Shen (lshen)
Cc: Sridharan Ramaswamy (srramasw);
lustre-discuss@clusterfs.com; cliff white
Subject: Re: [Lustre-discuss] Logical volumes over Lustre
storage
Nathan -
This looks like a feature we should get asap, and a very small
one to prepare probably.
Sridaran -
With this OST file systems (and MDT file systems) can be grown
(online) using LVM growth followed by ext3 dynamic resize. You can also
grow a Lustre file system by adding OST's.
In due course there will be tools to empty an OST with object
migration, and there might in due course be an ext4 online shrinker
(there is an offline shrinker for ext2 - but it doesn't support extents
as far as I know).
- Peter -
Lin Shen (lshen) wrote:
On a related question, this is what Andreas said:
On Dec 21, 2006 16:41 -0800, Lin Shen (lshen) wrote:
> Can a Luster file system be expanded on fly if it's
created on a
> logical volume by adding space to the logical volume?
You can add OSTs on the fly in 1.6, but not 1.4.
You could also grow the LV dynamically, but there is no
way to pass the ioctl to ext3 to do the online resizing. That might at
least be possible to implement in 1.6 because there is at least a
mountpoint for every device, but it doesn't work quite yet.
Does this mean whatever resizing that has been done on
the underline LVM, it won't been
reflected to the OST?
BTW, is it a big effort to implement the missing part,
ie., passing ioctl to ext3 for online resizing?
lin
________________________________
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Peter Braam
Sent: Tuesday, January 09, 2007 5:18 PM
To: Sridharan Ramaswamy (srramasw)
Cc: lustre-discuss@clusterfs.com; cliff white
Subject: Re: [Lustre-discuss] Logical volumes
over Lustre storage
Hi
You can also put your OST's on LVM's and get
some flexibility wit resizing, but probably you had already figured that
out!
- Peter -
Sridharan Ramaswamy (srramasw) wrote:
Nathan, Cliff - Thanks for the
clarification!
Think I understand this more now. Lustre
can grow at the granularity of
LUN size by adding it as another OST.
Not in between. I presume the
scenario is same for
reduce/decreasing(take an OST offline and add to
another MDT).
- Sridhar
-----Original Message-----
From: cliff white
[mailto:[EMAIL PROTECTED]
Sent: Tuesday, January 09, 2007 11:21 AM
To: Nathaniel Rutman
Cc: Sridharan Ramaswamy (srramasw);
lustre-discuss@clusterfs.com
Subject: Re: [Lustre-discuss] Logical
volumes over Lustre storage
Nathaniel Rutman wrote:
Sridharan Ramaswamy (srramasw) wrote:
Is it possible to get traditional LVM
like functionality
over Lustre
based storage?
My understanding is Lustre can aggregate
storage OSTs to provide a
single mount point. But the aggregate
storage it provides can't be
carved out into different logical
volumes, is this correct?
For eg, assume each OST is 8GB
node1: OST1, OST2, MDT
node2: OST3, OST4
Using *single* Lustre instance is it
possible to provide two mount
points with 16GB each? And ability to
administratively change the
storage available to each of those mount
points, say
instead of 16GB
each to 20GB and 12GB. Something similar
to lvextend, lvreduce.
As Nathan mentions below you will be
able to dynamically add
OSTS in the
future. However, you can _not split a
single partition between two
filesystems (which is possible with LVM)
so you would not be
able to split the 8GB LUN. You could
start with 16GB, add an 8GB LUN
and grow to 24GB, (You can do this
today, but you have to stop the
filesystem to change the config) but you
could not add 1/2
the LUN. So a
12GB/20GB split with 8 GB LUNS is not
possible, and will not
be possible
in the future.
cliffw
I presume you can achieve something like
the above by creating two
Lustre instances(running in different
ports) and mount
them separately
as 16GB filesystem. But that seems too
much overhead.
They don't have to run in different
ports, but yes, you can
achieve what
you want by making two different Lustre
filesystems. That
does mean you
need two different MDTs. (Similarly,
you would have to have two
different filesystems on your LVM.)
In Lustre 1.6 you can dynamically add
OSTs to a filesystem
to increase
the space available.
Appreciate any insights on this area.
thanks,
Sridhar
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