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Old 02-04-2010, 08:09 PM
Drew
 
Default Clustering

>>> Just wanted to get the lists opinion on clustering and what project to
>>> use. Any info would be greatly appreciated.
>>> Thanks
>>
>> There are all types of clustering. What are you looking to do?
>
> I guess the main objective would be availability.

We need more information then just an "Availability Cluster."

What application(s) do you want to cluster? What sort of
environment/budget are you working with? What objective(s) are you
trying to achieve? What are your expectations of the cluster itself,
beyond just high availability?


--
Drew

"Nothing in life is to be feared. It is only to be understood."
--Marie Curie
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Old 02-04-2010, 08:17 PM
"Bo Lynch"
 
Default Clustering

On Thu, February 4, 2010 4:09 pm, Drew wrote:
>>>> Just wanted to get the lists opinion on clustering and what project to
>>>> use. Any info would be greatly appreciated.
>>>> Thanks
>>>
>>> There are all types of clustering. What are you looking to do?
>>
>> I guess the main objective would be availability.
>
> We need more information then just an "Availability Cluster."
>
> What application(s) do you want to cluster? What sort of
> environment/budget are you working with? What objective(s) are you
> trying to achieve? What are your expectations of the cluster itself,
> beyond just high availability?
>
>
> --
> Drew
>
Right know we have about 30 or so linux servers scattered through out or
district. Was looking at ways of consolidating and some sort of redundancy
would be nice.
Will clustering not work with certain apps? We have a couple mysql dbases,
oracle database, smb shares, nfs, email, and web servers.



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Old 02-04-2010, 09:57 PM
"nate"
 
Default Clustering

Bo Lynch wrote:

> Right know we have about 30 or so linux servers scattered through out or
> district. Was looking at ways of consolidating and some sort of redundancy
> would be nice.
> Will clustering not work with certain apps? We have a couple mysql dbases,
> oracle database, smb shares, nfs, email, and web servers.

Maybe your looking for putting them in a virtual environment,
to cluster applications like that is fairly complex, Oracle has it's
own clustering(RAC), MySQL has clustering(with some potentially serious
limitations depending on your DB size), NFS clustering is yet another
animal, and samba clustering, well CIFS is a stateful protocol so
there really isn't a good way to do clustering there at least with
generic samba, that I'm aware of, if a server fails the clients
connected to it will lose their connection and potentially data if
they happened to be writing at the time.

In any case it sounds like clustering isn't want your looking for, I
would look towards putting the systems in VMs with HA shared storage
if you want to consolidate and provide high availability.

nate


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Old 02-04-2010, 10:18 PM
Drew
 
Default Clustering

> Right know we have about 30 or so linux servers scattered through out or
> district. Was looking at ways of consolidating and some sort of redundancy
> would be nice.

I'm in the process of going through something like that right now. The
solution we're pursuing is to virtualize our existing physical servers
in virtual machines and consolidating those VM's on a smaller number
of larger servers.

The tools we're using allow us to keep a warm copy of a VM on
redundant server and if we lose an entire server we're up within
3-5min with minimal data loss. As the servers we're installing have
VMware ESXi embedded in the server and storage is pulled from
redundant iSCSI backends, data loss due to server failure is minimal.
And as part of the backup process includes regular off-site backups of
the data and VMs to another office we can, in theory, lose an entire
building and still continue to function.


--
Drew

"Nothing in life is to be feared. It is only to be understood."
--Marie Curie
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Old 02-04-2010, 10:34 PM
Les Mikesell
 
Default Clustering

On 2/4/2010 3:17 PM, Bo Lynch wrote:
>
> Right know we have about 30 or so linux servers scattered through out or
> district. Was looking at ways of consolidating and some sort of redundancy
> would be nice.
> Will clustering not work with certain apps? We have a couple mysql dbases,
> oracle database, smb shares, nfs, email, and web servers.

Each app has it's own best way to provide the redundancy and
auto-failover and it's own set of tradeoffs of the added complexity vs.
the possible reduced downtime if the primary fails.

I'd balance the options against the low-tech method of having raid
mirrors in swappable bays with a spare similar server chassis or two
around plus regular backups kept at a different location. The raid lets
you continue in the likely event of a disk failure so you can repair it
at a convenient time. Other failures (motherboard, power supply) are
less likely but can be handled by swapping the drives into an alternate
chassis (and with Centos you'll need to re-assign the IP addresses that
are tied to the old NIC mac addresses) with a small amount of downtime.
And the backups cover things like operator or software errors (that
would wipe a cluster too) or a building-level disaster that destroys the
disks or the primary and spare chassis at the same time. Some apps may
be worth the effort to do better.

--
Les Mikesell
lesmikesell@gmail.com
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Old 02-05-2010, 10:54 AM
"Simon Billis"
 
Default Clustering

Hi,

> On 2/4/2010 3:17 PM, Bo Lynch wrote:
> >
> > Right know we have about 30 or so linux servers scattered through out
> or
> > district. Was looking at ways of consolidating and some sort of
> redundancy
> > would be nice.
> > Will clustering not work with certain apps? We have a couple mysql
> dbases,
> > oracle database, smb shares, nfs, email, and web servers.
>
> Each app has it's own best way to provide the redundancy and
> auto-failover and it's own set of tradeoffs of the added complexity vs.
> the possible reduced downtime if the primary fails.
>
> I'd balance the options against the low-tech method of having raid
> mirrors in swappable bays with a spare similar server chassis or two
> around plus regular backups kept at a different location. The raid
> lets
> you continue in the likely event of a disk failure so you can repair it
> at a convenient time. Other failures (motherboard, power supply) are
> less likely but can be handled by swapping the drives into an alternate
> chassis (and with Centos you'll need to re-assign the IP addresses that
> are tied to the old NIC mac addresses) with a small amount of downtime.
> And the backups cover things like operator or software errors (that
> would wipe a cluster too) or a building-level disaster that destroys
> the
> disks or the primary and spare chassis at the same time. Some apps may
> be worth the effort to do better.

In our configurations we utilise different strategies depending on what we
want to achieve as there isn't really a panacea for this... We use virtual
servers, hot standby firewalls/routers, load balanced servers, warm standby
servers (using such things as mysql replication, rsync and DRBD to keep the
boxes in sync) and shared storage from disk arrays and servers with local
disk arrays for local performance and resilience. We have also utilised
hadoop (distributed filesystem) on some again to provide resilience within
the limitations of hadoop.

S.


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