f



Using ASM for shared linux filesystem storage?

Hey;

The dba team and I (UNIX admin) are being asked to create a shared ext4 fil=
esystem across a number of nodes.  I believe this is to enable us to remove=
 Veritas Cluster Filesystem (VCFS); but, that's just a suspicion.

So, the questions: has anyone used ASM to create a shared storage filesyste=
m across nodes that are not in any way otherwise related to oracle products=
?  I know the dbas create shared filesystems via CRS; however, I've not see=
n ext4 being used.  Is that possible/supported/a good idea?
=20
If anyone has any information, documentation, etc, I'd appreciate getting a=
 pointer.
=20
thanks for your time.
=20
Doug O'Leary
0
dkoleary
7/30/2016 12:19:14 PM
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On 30.07.2016 14:19, dkoleary@olearycomputers.com wrote:

> The dba team and I (UNIX admin) are being asked to create a shared
> ext4 filesystem across a number of nodes.  I believe this is to
> enable us to remove Veritas Cluster Filesystem (VCFS); but, that's
> just a suspicion.

That is odd: they want a filesystem that is intended to live in a single 
block device to be created as replacement for a cluster filesystem?  I 
mean, there are free and open source cluster filesystems around, why not 
pick those?  I am thinking of

  - GlusterFS
  - GFS
  - CephFS
  - Lustre
  - maybe even OCFS
  - more at [1]

For an ext4 you need a single block device.  So to have it distributed 
you need a distributed block device.  Maybe you can pull off something 
like this with DRBD but as far as I understand the whole block device is 
mirrored on every node.  It seems to me that a technical superior 
solution is a networked file system because at the filesystem level you 
have much more knowledge about the data, distribution and failover needs 
than on the block device level.  Higher level, more semantic - it's as 
easy as that.

> So, the questions: has anyone used ASM to create a shared storage
> filesystem across nodes that are not in any way otherwise related to
> oracle products?  I know the dbas create shared filesystems via CRS;
> however, I've not seen ext4 being used.  Is that possible/supported/a
> good idea?

I'd think it's not a good idea.  Minimum, one would need more 
information where that requirement to make it ext4 came from to come to 
a more informed conclusion.

> If anyone has any information, documentation, etc, I'd appreciate
> getting a pointer.

I hope I provided some.

Kind regards

	robert


[1] 
https://en.wikipedia.org/wiki/List_of_file_systems#Distributed_file_systems

-- 
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/
0
Robert
7/30/2016 4:30:32 PM
Hey, Robert;

Thanks for the response.  I'm hearing rumors that sanity may be prevailing.=
  I'm on a trip atm, and the only thing I saw was the service call asking f=
or this to happen.

We (a minion and I) keyed in on the non-cluster aware filesystem on a clust=
ered disk storage contradiction as well.  Other that common sense, I was ho=
ping for a link which said "these are the filesystems that oracle supports =
on ASM".  My googling didn't show anything like that, though.

If it turns out that sanity doesn't prevail, we'll have to start the push b=
ack.

Thanks again for the info and for the link  Haven't looked at it yet but it=
's definitely on the to-do list.

Doug 
0
Doug
7/30/2016 6:16:44 PM
On 30.07.2016 20:16, Doug OLeary wrote:

> Thanks for the response.  I'm hearing rumors that sanity may be
> prevailing.  I'm on a trip atm, and the only thing I saw was the
> service call asking for this to happen.

It's always good if sanity gets the upper hand.  There is just too much 
confusion out there.  Good luck!

> We (a minion and I) keyed in on the non-cluster aware filesystem on a
> clustered disk storage contradiction as well.  Other that common
> sense, I was hoping for a link which said "these are the filesystems
> that oracle supports on ASM".  My googling didn't show anything like
> that, though.

Unfortunately my active ASM usage is too long ago to be of much help 
here.  I tend to believe though, that you cannot have an ASM volume 
appear as a block device in the OS - which is what you would need.  I 
tried to dig around a bit but only found sites discussing usage of a 
block device for storage of ASM - not how you can make an ASM disk 
appear as a block device.

And if you think about it, this makes sense: Oracle database does not 
need a filesystem.  It just needs something where to store blocks for 
each data "file" in random access manner.  ASM gives you that and there 
does not seem to be any need to expose ASM volumes other than through 
some libraries that the database is using.

> If it turns out that sanity doesn't prevail, we'll have to start the
> push back.

:-)

> Thanks again for the info and for the link  Haven't looked at it yet
> but it's definitely on the to-do list.

You're welcome!  Please do keep us updated.  It's always interesting to 
see what eventually turns up.

Kind regards

	robert

-- 
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/
0
Robert
7/31/2016 9:03:55 AM
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