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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