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Old 04-23-2010, 01:44 AM
James
 
Default iSCSI / GFS shared web server file system

On 4/22/2010 6:51 PM, John R Pierce wrote:
> jchase wrote:
>
>> We currently have a MD3000i with an iSCSI LUN shared out to our apache
>> web server. We are going to add another apache web server into the mix
>> using LVS to load balance, however, I am curious how well iSCSI
>> handles file locking and data integrity. ...
>>
> it doesn't, not even close. iscsi is purely a block device protocol,
> it doesn't know what files are.
>
That was kind of a stupid assumption on my part and major
misinterpretation of iSCSI information
>
>> Is my setup totally flawed and will ext3 not allow for data integrity
>> with multiple apache hosts reading/writing to the shared storage? Am I
>> required to also setup GFS across my apache hosts or does iSCSI
>> somehow manage this?
>>
> NFS would be more suitable for this application.
>
Is there any reason why you suggest NFS? We would then need to run a NFS
server and deal with the complexity of having a failover solution for
that, whereas it seemed like GFS is a little more decentralized (at
least in terms of not relying on a specific file server) after you
configure the cluster environment.

That was my impression from reading through the docs anyways. I've never
set it up.
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Old 04-23-2010, 02:39 AM
"nate"
 
Default iSCSI / GFS shared web server file system

James wrote:

> That was my impression from reading through the docs anyways. I've never
> set it up.

my impression is GFS requires shared storage, I believe there
are ways around it, but take a look at this for setting up GFS
for use with NFS

http://sources.redhat.com/cluster/doc/nfscookbook.pdf

I think it'd be much easier if you just replicate the data between
the servers with rsync or something. GFS sounds like way overkill
for a couple of web servers.

nate

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Old 04-23-2010, 07:10 AM
"Geoff Galitz"
 
Default iSCSI / GFS shared web server file system

> my impression is GFS requires shared storage, I believe there
> are ways around it, but take a look at this for setting up GFS
> for use with NFS


iSCSI provides the basic foundation needed by GFS for shared storage, so the
OP is good for that. GFS, however, is not exactly a simple technology to
deploy. NFS is better for more standardized infrastructures where resources
and time may be limited. GFS and other shared/clustering filesystems are
great, but don't underestimate the resources needed to feed and care for
them.

OCSF2 over iSCSI is a good option to look at, too. There is also gluster.
But NFS is going to be the mainstream approach with the best support and
administration options unless the OP is running into some technical
limitations.


---------------------------------
Geoff Galitz
Blankenheim NRW, Germany
http://www.galitz.org/
http://german-way.com/blog/



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Old 04-23-2010, 08:46 AM
Hakan Koseoglu
 
Default iSCSI / GFS shared web server file system

On Fri, Apr 23, 2010 at 8:10 AM, Geoff Galitz <geoff@galitz.org> wrote:
> OCSF2 over iSCSI is a good option to look at, too. *There is also gluster.
> But NFS is going to be the mainstream approach with the best support and
> administration options unless the OP is running into some technical
> limitations.
I have a number of OCFS2 over plain old SCSI with MD3000 setups. The
older versions have a couple of stupid bugs so it's always better to
move to the most upto date version of the module from Oracle. I
haven't tried it with iSCSI. I haven't tried Gluster yet but I find
OCFS2 quite maintenance-free until you hit the damn bug!
--
Hakan (m1fcj) - http://www.hititgunesi.org
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Old 04-23-2010, 05:00 PM
James
 
Default iSCSI / GFS shared web server file system

> http://sources.redhat.com/cluster/doc/nfscookbook.pdf
>
> I think it'd be much easier if you just replicate the data between
> the servers with rsync or something. GFS sounds like way overkill
> for a couple of web servers.
>
Maybe you're right that GFS would be overkill -- I know you have to
setup the whole clustering environment before it will work. Even though
NFS would be easy to setup, it seems like it would just add more servers
into the mix. We really want to achieve automatic failover at all levels
and setting up NFS to replicate in real time and run the extra servers
for that seems like it would require more resources. I'd rather put the
time into understanding the complexities of the clustering environment
setup and management and save some server sprawl

I'll look into OCFS2 and gluster to see if those are good options.
Thanks for those suggestions.
> nate
>
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Old 04-24-2010, 08:31 PM
Ross Walker
 
Default iSCSI / GFS shared web server file system

On Apr 23, 2010, at 1:00 PM, James <jchase@mandaladesigns.com> wrote:

>
>> http://sources.redhat.com/cluster/doc/nfscookbook.pdf
>>
>> I think it'd be much easier if you just replicate the data between
>> the servers with rsync or something. GFS sounds like way overkill
>> for a couple of web servers.
>>
> Maybe you're right that GFS would be overkill -- I know you have to
> setup the whole clustering environment before it will work. Even
> though
> NFS would be easy to setup, it seems like it would just add more
> servers
> into the mix. We really want to achieve automatic failover at all
> levels
> and setting up NFS to replicate in real time and run the extra servers
> for that seems like it would require more resources. I'd rather put
> the
> time into understanding the complexities of the clustering environment
> setup and management and save some server sprawl
>
> I'll look into OCFS2 and gluster to see if those are good options.
> Thanks for those suggestions.

Web servers are mostly read-only, so unless your web servers are going
to do a lot of writing to shared storage I would simply use rsync to a
local disk in each server, or use NFS, even NFS and heartbeat for
redundancy will be 100 times simpler to setup and maintain.

GFS/OCFS2/Gluster/Lustre are really for multi-writers to shared
storage such as a large NFS server cluster (4-8-16 nodes) serving
thousands of clients for general file services, not thousands of
clients accessing shared storage directly.

-Ross


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Old 04-27-2010, 10:27 PM
James
 
Default iSCSI / GFS shared web server file system

> Web servers are mostly read-only, so unless your web servers are going
> to do a lot of writing to shared storage I would simply use rsync to a
> local disk in each server, or use NFS, even NFS and heartbeat for
> redundancy will be 100 times simpler to setup and maintain.
>
> GFS/OCFS2/Gluster/Lustre are really for multi-writers to shared
> storage such as a large NFS server cluster (4-8-16 nodes) serving
> thousands of clients for general file services, not thousands of
> clients accessing shared storage directly.
>
It's a good point. Thanks for making it. OCFS2 seems like a pain to
maintain with new rpm's for each new kernel update, and GFS a pain to
setup at the least.

We just want scalability for future hosting options; it seems like GFS
is the most powerful option. But you're right that there is not a lot of
writing going on and NFS is probably the best option.
> -Ross
>
>
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