GossipingPropertyFileSnitch vs Ec2Snitch

[John Wong <go...@gmail.com>]

Hi

Based on
*
http://docs.datastax.com/en/cassandra/2.0/cassandra/architecture/architectureSnitchEC2_t.html
*
http://docs.datastax.com/en/cassandra/2.0/cassandra/architecture/architectureSnitchGossipPF_c.html

What other benefits can Ec2Snitch provide in a single-region, multi-az AWS
deployment besides automatically setting dc and rack for you as the snitch
reads from EC2 metadata.
Obviously there is a concern with what if there is something wrong with the
metadata server...

Thanks.
John

Re: GossipingPropertyFileSnitch vs Ec2Snitch

[Robert Coli <rc...@eventbrite.com>]

On Fri, Aug 21, 2015 at 2:37 AM, Alain RODRIGUEZ <ar...@gmail.com> wrote:

> So what would be the procedure to go from EC2Snitch to GPFS ?
>
> I see 2 possibilities and I am not sure of the result of each of these:
>
> - Node by node, on a rolling restart way, and making sure that you use the
> former DC names and racks. Copying the EC2 network. Would this be doable or
> would that need a full cluster restart at once ?
> - Add the new DC using directly GPFS on all the node without modifying the
> old one (hybride: 1 DC EC2Snitch, 1 DC GPFS), again copying the EC2 DCs and
> racks. Would this work ?
>

I believe both of these would work. If you have the extra nodes I probably
would do the additional-DC method.

I also recommend :

1) get a list of one or more partition keys for all ranges in your cluster
2) test them with nodetool getendpoints before changing snitch
3) test them with nodetool getendpoints after changing snitch


> Also, Is this need of mirroring the exact DC and racks name mandatory in
> those 2 procedures as I think it is ?
>

In the spoof-ec2snitch method, yes. If you don't, Very Bad Things will
happen.

In the additional-DC method, it doesn't matter what you call the new DC or
racks, just that they are configured properly.

=Rob

Re: GossipingPropertyFileSnitch vs Ec2Snitch

[Alain RODRIGUEZ <ar...@gmail.com>]

Hi guys,

I am also wondering about this kind of stuff, since we are going out of AWS
and were using EC2Snitch. I felt free to write it here, since it looks
linked to previous comments.

@John, we have been using EC2Snitch for many years, and it just works fine
! Plus, we don't have to keep the GPFS file up to date every time we add a
node or remove one. EC2Snitch is quite strait-forward and easy to use. The
first "issue" we have today, is indeed to add a new DC from outside AWS. I
am trying to find out how to do that right now. If we figure out that this
is easy, you can perfectly go with EC2Snitch imho.

So what would be the procedure to go from EC2Snitch to GPFS ?

I see 2 possibilities and I am not sure of the result of each of these:

- Node by node, on a rolling restart way, and making sure that you use the
former DC names and racks. Copying the EC2 network. Would this be doable or
would that need a full cluster restart at once ?
- Add the new DC using directly GPFS on all the node without modifying the
old one (hybride: 1 DC EC2Snitch, 1 DC GPFS), again copying the EC2 DCs and
racks. Would this work ?

Also, Is this need of mirroring the exact DC and racks name mandatory in
those 2 procedures as I think it is ?

I think this worth a good testing anyway.

C*heers,

Alain

2015-08-03 22:04 GMT+02:00 John Wong <go...@gmail.com>:

> Thanks Rob.
>
> But even if we do move out of EC2 in X years, unlike partitioner, I don't
> think there is much to do to switch snitch. Yes, I am evaluating if there
> is actually good benefit to use EC2.
>
> John
>
> On Mon, Aug 3, 2015 at 1:54 PM, Robert Coli <rc...@eventbrite.com> wrote:
>
>> On Sun, Aug 2, 2015 at 6:22 PM, John Wong <go...@gmail.com> wrote:
>>
>>> What other benefits can Ec2Snitch provide in a single-region, multi-az
>>> AWS deployment besides automatically setting dc and rack for you as the
>>> snitch reads from EC2 metadata.
>>> Obviously there is a concern with what if there is something wrong with
>>> the metadata server...
>>>
>>
>> GPFS is broadly similar to EC2Snitch/EC2MRSnitch, but is usable if you
>> for example have a DR site outside of EC2.
>>
>> In general I'd probably suggest using GPFS unless you're really sure
>> you'll always be in EC2, forever and always.
>>
>> =Rob
>>
>>
>
>

Re: GossipingPropertyFileSnitch vs Ec2Snitch

[John Wong <go...@gmail.com>]

Thanks Rob.

But even if we do move out of EC2 in X years, unlike partitioner, I don't
think there is much to do to switch snitch. Yes, I am evaluating if there
is actually good benefit to use EC2.

John

On Mon, Aug 3, 2015 at 1:54 PM, Robert Coli <rc...@eventbrite.com> wrote:

> On Sun, Aug 2, 2015 at 6:22 PM, John Wong <go...@gmail.com> wrote:
>
>> What other benefits can Ec2Snitch provide in a single-region, multi-az
>> AWS deployment besides automatically setting dc and rack for you as the
>> snitch reads from EC2 metadata.
>> Obviously there is a concern with what if there is something wrong with
>> the metadata server...
>>
>
> GPFS is broadly similar to EC2Snitch/EC2MRSnitch, but is usable if you for
> example have a DR site outside of EC2.
>
> In general I'd probably suggest using GPFS unless you're really sure
> you'll always be in EC2, forever and always.
>
> =Rob
>
>

Re: GossipingPropertyFileSnitch vs Ec2Snitch

[Robert Coli <rc...@eventbrite.com>]

On Sun, Aug 2, 2015 at 6:22 PM, John Wong <go...@gmail.com> wrote:

> What other benefits can Ec2Snitch provide in a single-region, multi-az AWS
> deployment besides automatically setting dc and rack for you as the snitch
> reads from EC2 metadata.
> Obviously there is a concern with what if there is something wrong with
> the metadata server...
>

GPFS is broadly similar to EC2Snitch/EC2MRSnitch, but is usable if you for
example have a DR site outside of EC2.

In general I'd probably suggest using GPFS unless you're really sure you'll
always be in EC2, forever and always.

=Rob