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: [email protected]; 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);
[email protected]
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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