Data Storage - Multiple servers access to single shared resource point

Author

Multiple servers access to single shared resource point

felixhan@gmail.com

2006-09-19, 7:14 am

Hi,

I am newbie in storage.

I have installed two servers in 2003 Edition. The two servers are
using EVA8000 SAN, and I have created a LUN with 500GB and shared it.
So, now two servers are able to look at this single point of LUN and
access the files. Now the question is I am not able to see the changes
from B server if A server did a change on the files. Any configuration
that I can do on 2003 Edition so that both A & B servers can see the
changes simultaneously? Any documentation from Microsoft can show
this?

Thanks for any input you may have. Appreciate.

Bill Todd

2006-09-19, 7:14 am

felixhan@gmail.com wrote:
> Hi,
>
> I am newbie in storage.
>
> I have installed two servers in 2003 Edition. The two servers are
> using EVA8000 SAN, and I have created a LUN with 500GB and shared it.
> So, now two servers are able to look at this single point of LUN and
> access the files. Now the question is I am not able to see the changes
> from B server if A server did a change on the files. Any configuration
> that I can do on 2003 Edition so that both A & B servers can see the
> changes simultaneously? Any documentation from Microsoft can show
> this?

No: no Microsoft products support this kind of operation, though some
third-party products do. Search for SANergy (an IBM Tivoli product) -
it should have enough information available to get you started, though
even SANergy isn't a truly distributed product: it serves data directly
to its clients, but only after mediation through a central metadata
server (for a truly distributed architecture you've got to look to
systems like VMS or perhaps Parallel Sysplex, unless you consider
open-source efforts like GFS ready for prime time, and I don't know if
even that runs on Windows).

The bottom line is that sharing storage this way is a complex endeavor:
while some products exist that can help make it achievable by
'newbies', at least in the limited sense that SANergy does it, NAS
products are far easier to use for simple shared-storage needs.

- bill

Faeandar

2006-09-20, 7:15 am

On Tue, 19 Sep 2006 03:45:12 -0400, Bill Todd <billtodd@metrocast.net>
wrote:

>felixhan@gmail.com wrote:
>
>No: no Microsoft products support this kind of operation, though some
>third-party products do. Search for SANergy (an IBM Tivoli product) -
>it should have enough information available to get you started, though
>even SANergy isn't a truly distributed product: it serves data directly
>to its clients, but only after mediation through a central metadata
>server (for a truly distributed architecture you've got to look to
>systems like VMS or perhaps Parallel Sysplex, unless you consider
>open-source efforts like GFS ready for prime time, and I don't know if
>even that runs on Windows).
>
>The bottom line is that sharing storage this way is a complex endeavor:
> while some products exist that can help make it achievable by
>'newbies', at least in the limited sense that SANergy does it, NAS
>products are far easier to use for simple shared-storage needs.
>
>- bill

GFS does not run on windows but Polyserve does. It's a true clustered
file system on Windows, and not an easy beast to master. It's simple
enough to load and get started but maintaning it and all it's foibles
is frustrating. But it does work, mostly.

NAS is indeed far easier to use and manage for multi-host write
access.

~F

Bill Todd

2006-09-20, 7:15 am

Faeandar wrote:
> On Tue, 19 Sep 2006 03:45:12 -0400, Bill Todd <billtodd@metrocast.net>
> wrote:
>
>
> GFS does not run on windows but Polyserve does. It's a true clustered
> file system on Windows, and not an easy beast to master. It's simple
> enough to load and get started but maintaning it and all it's foibles
> is frustrating. But it does work, mostly.

Thanks - I keep forgetting about them, as they're somewhat newer on the
scene than most. I really ought to look at them more closely, since
handling metadata in a truly distributed manner is a difficult job that
tends to lead to interesting solutions (well, Parallel Sysplex's
solution may mostly be strange-mainframe-itis and VMS's solution may be
more antiquated than 'interesting', but the latter was certainly
leading-edge technology for its era).

- bill

Ed Wilts

2006-09-21, 1:14 pm

Ed Wilts

2006-09-21, 1:14 pm

Faeandar wrote:
> GFS does not run on windows but Polyserve does. It's a true clustered
> file system on Windows, and not an easy beast to master. It's simple
> enough to load and get started but maintaning it and all it's foibles
> is frustrating. But it does work, mostly.

It can also be *very* slow. We worked with Polyserve on a cluster
implementation and finally ripped it all out. It was significantly
slower than a Windows cluster.

> NAS is indeed far easier to use and manage for multi-host write
> access.

NAS doesn't really solve the problem. You need a cluster lock manager.
Until you have one, there's absolutely nothing you can do without
corrupting the file system. If you purchase something like a NetApp
NAS Filer, then the Filer provides the cluster lock manager.

You can rip out the Windows installation and install a VMS cluster.
Then you'll finally have a true active/active cluster file system...

.../Ed

Bill Todd

2006-09-21, 1:14 pm

Ed Wilts wrote:
> Faeandar wrote:

....

>
> NAS doesn't really solve the problem. You need a cluster lock manager.

You are seriously confused: NAS does solve the problem and you don't
need a cluster lock manager.

A semi-distributed system like SANergy can also solve the problem
without a cluster lock manager, as long as all accesses are funneled
through a central metadata server that performs the locking centrally
(as a normal NAS server does) even while distributing the loads of the
actual data movement to satellite data servers.

> Until you have one, there's absolutely nothing you can do without
> corrupting the file system.

As described above, this is simply not true. A distributed lock manager
is required to keep file-system data coherent only when multiple clients
access that data at a level *below* that of the file system interface
(and hence cannot benefit from the local locking mechanisms within that
interface) - and not necessarily even then if a central coordinator
exists as with products like SANergy and it mediates locking while its
satellites serve up the underlying data.

If you purchase something like a NetApp
> NAS Filer, then the Filer provides the cluster lock manager.

No, there's nothing cluster-like about it: it simply performs *central*
locking services for the data that it exports just as any conventional
file server (or for that matter local file system) does.

- bill

_firstname_@lr_dot_los-gatos_dot_ca.us

2006-09-21, 7:14 pm

In article <1158848532.499152.119460@b28g2000cwb.googlegroups.com>,
Ed Wilts <ewilts@ewilts.org> wrote:
>This is not a storage issue - it's an OS issue.

Wrong. It is a storage software issue. It depends on what file
system you use - and file systems are typically considered storage
software. Typically, some simple file systems are delivered together
with the OS (this includes NTFS, ext3 and such). High-end file
systems (this term includes NAS services and clustered or distributed
file systems) are usually an after-market offering; those are often
integrated with storage device offerings (for example, it would be
silly to buy the PanFS file system, unless you also buy Panasas
storage servers).

- For example, a traditional NAS box (like a NetApp) is two things in
one: A file system backend (in this particular case WAFL), with a
file-transport protocol frontend (in this particular case NFS and
others).

- A traditional cluster file system (like Lustre, GPFS or Sistina/GFS)
takes every node in the cluster and makes it both a file system
service consumer (a.k.a. file system client), and a file system
service provider (a.k.a. data or metadata server). Often occurs
with SAN file systems, where access to the data is directly to
shared disks.

- Then there are interesting hybrid models, typically with many file
system clients being served by a central (cluster of) metadata
servers, with access to the data either being through the data
servers (sometimes co-located with the metadata servers), and
sometimes directly over a SAN or a SAN-like network infrastructure.
Lustre, StorageTank = SAN-FS, SANergy, and many other offerings are
in this category.

- Good old VAXcluster is a hybrid, which can be either of the three
(sometimes with help from the HSC, which is somewhat similar to a
modern object disk). In my recollection, IBM sysplex is more like a
non-hierarchical cluster file system, although I'm not an expert on
that.

The lock manager is an important part of every file system. In the
trivial single-node non-shared file systems, the lock manager is
invisible, and also is trivially small (it just has to preserve
invariants within on kernel). In all shared or clustered file systems
the lock managers tend to be very interesting. There are some cases
where file systems used outboard lock managers (the original Minnesota
GFS, pre-Sistina, comes to mind).

> Microsoft Windows 2003
>does not have a cluster file system.

What do you mean by "does not have" here?

If you mean "Windows 2003 does not ship with a cluster or distributed
file system pre-installed", you are correct.

If you mean "No cluster or distributed file systems are available for
Windows 200x", you are very very wrong. Many are available. Some are
no-purchase-cost (often known as "free" or "open source"). Others are
expensive. Some require hardware purchases for the file servers,
others don't, and can rely on any storage. Some can integrate with
other operating systems (most importantly Linux and commercial
Unix'es), others can't.

> You need to clsuter the 2 servers
>and present the LUN as a cluster resource. It will be active on only 1
>node at a time - active/active is *NOT* supported.

This is true for the simplest use of a single-instance file system
(like NTFS) on a shared LUN. There are many ways to cluster many
servers, using everything from simple NAS services to high-end
multi-tiered distributed file systems, often with active/active
storage and parallel access.

--
The address in the header is invalid for obvious reasons. Please
reconstruct the address from the information below (look for _).
Ralph Becker-Szendy _firstname_@lr_dot_los-gatos_dot_ca.us

carmelomcc

2006-09-23, 7:13 pm

There are nurmous cluster filesystems that will work for your solution.

IE:

Windows
http://www.polyserve.com/matrix_server_windows.php

http://www.veritas.com

The real question is why do you need this? Is it for a high end
application or simple file sharing? If it is simple file sharing you
may want to use another solution. You would be making this overly
complicated for no reason.

Check out freenas.org they offer a linux OS specifc to nas that you can

use. It will install on the existing hardware that you are using and
provide CIFS access to the windows machines.

_firstname_@lr_dot_los-gatos_dot_ca.us wrote:
> In article <1158848532.499152.119460@b28g2000cwb.googlegroups.com>,
> Ed Wilts <ewilts@ewilts.org> wrote:
>
> Wrong. It is a storage software issue. It depends on what file
> system you use - and file systems are typically considered storage
> software. Typically, some simple file systems are delivered together
> with the OS (this includes NTFS, ext3 and such). High-end file
> systems (this term includes NAS services and clustered or distributed
> file systems) are usually an after-market offering; those are often
> integrated with storage device offerings (for example, it would be
> silly to buy the PanFS file system, unless you also buy Panasas
> storage servers).
>
> - For example, a traditional NAS box (like a NetApp) is two things in
> one: A file system backend (in this particular case WAFL), with a
> file-transport protocol frontend (in this particular case NFS and
> others).
>
> - A traditional cluster file system (like Lustre, GPFS or Sistina/GFS)
> takes every node in the cluster and makes it both a file system
> service consumer (a.k.a. file system client), and a file system
> service provider (a.k.a. data or metadata server). Often occurs
> with SAN file systems, where access to the data is directly to
> shared disks.
>
> - Then there are interesting hybrid models, typically with many file
> system clients being served by a central (cluster of) metadata
> servers, with access to the data either being through the data
> servers (sometimes co-located with the metadata servers), and
> sometimes directly over a SAN or a SAN-like network infrastructure.
> Lustre, StorageTank = SAN-FS, SANergy, and many other offerings are
> in this category.
>
> - Good old VAXcluster is a hybrid, which can be either of the three
> (sometimes with help from the HSC, which is somewhat similar to a
> modern object disk). In my recollection, IBM sysplex is more like a
> non-hierarchical cluster file system, although I'm not an expert on
> that.
>
> The lock manager is an important part of every file system. In the
> trivial single-node non-shared file systems, the lock manager is
> invisible, and also is trivially small (it just has to preserve
> invariants within on kernel). In all shared or clustered file systems
> the lock managers tend to be very interesting. There are some cases
> where file systems used outboard lock managers (the original Minnesota
> GFS, pre-Sistina, comes to mind).
>
>
> What do you mean by "does not have" here?
>
> If you mean "Windows 2003 does not ship with a cluster or distributed
> file system pre-installed", you are correct.
>
> If you mean "No cluster or distributed file systems are available for
> Windows 200x", you are very very wrong. Many are available. Some are
> no-purchase-cost (often known as "free" or "open source"). Others are
> expensive. Some require hardware purchases for the file servers,
> others don't, and can rely on any storage. Some can integrate with
> other operating systems (most importantly Linux and commercial
> Unix'es), others can't.
>
>
> This is true for the simplest use of a single-instance file system
> (like NTFS) on a shared LUN. There are many ways to cluster many
> servers, using everything from simple NAS services to high-end
> multi-tiered distributed file systems, often with active/active
> storage and parallel access.
>
> --
> The address in the header is invalid for obvious reasons. Please
> reconstruct the address from the information below (look for _).
> Ralph Becker-Szendy _firstname_@lr_dot_los-gatos_dot_ca.us