Hi,
We did indeed consider support for a mixed cluster, but in the end
decided against it, for many reasons:
- the internode protocol is underdocumented and keeps changing, so it
would be hard to support it, and hard to test it
- it would limit the kind of optimizations we can do by reducing our
freedom to change implementation details
- would users be willing to risk their production cluster by adding a
foreign node? many would not
- a cluster is as fast as its slowest node, so you wouldn't see
performance improvements until you've upgraded all of your nodes
So in the end, we went with our own internode protocol. We do have a
migration support tool (cqlproxy - duplicates cql requests to two
parallel clusters), and many users just add dual-write support to their
applications during the proof-of-concept/migration phase.
btw, you can do the stop/swap/start cycle; you just have to stop all
nodes for it. While that's not possible for many production clusters,
it is possible for others.
On 03/13/2017 09:17 AM, benjamin roth wrote:
@Dor,Jeff:
I think Jeff pointed out an important fact: You cannot stop CS, swap
binaries and start Scylla. To be honest that was AFAIR the only "Oooh
:(" I had when reading the Scylla "marketing material".
If that worked it would be very valuable from both Scylla's and a
users' point of view. As a user I would love to give scylla a try as
soon as it provides all the features my application requires. But the
hurdle is quite high. I have to create a separate scylla cluster and I
have to migrate a lot of data and I have to manage somehow that my
application can use (r+w) both CS + Scylla at the same time to not run
any risk of data loss or dead end road if something goes wrong. And
still: I would not be able to compare CS + Scylla for my workload
totally fair as the conditions changed. New hardware, maybe partial
dataset, probably only "test traffic".
However, if I was able to just replace a single node in an existing
cluster I'd have:
1. Superlow hurdle to give it a try: No risk, no effort
2. Fair comparison by comparing new node against some equally equipeed
old node in the same cluster with the same workload
3. Easy to make a decision if to continue or not
That would be totally awesome!
2017-03-12 23:16 GMT+01:00 Kant Kodali <k...@peernova.com
<mailto:k...@peernova.com>>:
I don't think ScyallDB guys started this conversation in the first
place to suggest or promote "drop-in replacement". It was
something that is brought up by one of the Cassandra users and
ScyallDB guys just clarified it. They are gracious enough to share
the internals in detail.
honestly, I find it weird when I see questions like whether a
question belongs to a mailing list or not especially in this
case. If one doesn't like it they can simply not follow the
thread. I am not sure what is the harm here.
On Sun, Mar 12, 2017 at 2:29 PM, James Carman
<ja...@carmanconsulting.com <mailto:ja...@carmanconsulting.com>>
wrote:
Well, looking back, it appears this thread is from 2015, so
apparently everyone is okay with it.
Promoting a value-add product that makes using Cassandra
easier/more efficient/etc would be cool, but coming to the
Cassandra mailing list to promote a "drop-in replacement" (use
us, not Cassandra) isn't cool, IMHO.
On Sun, Mar 12, 2017 at 5:04 PM Kant Kodali <k...@peernova.com
<mailto:k...@peernova.com>> wrote:
yes.
On Sun, Mar 12, 2017 at 2:01 PM, James Carman
<ja...@carmanconsulting.com
<mailto:ja...@carmanconsulting.com>> wrote:
Does all of this Scylla talk really even belong on the
Cassandra user mailing list in the first place?
On Sun, Mar 12, 2017 at 4:07 PM Jeff Jirsa
<jji...@apache.org <mailto:jji...@apache.org>> wrote:
On 2017-03-11 22:33 (-0700), Dor Laor
<d...@scylladb.com <mailto:d...@scylladb.com>> wrote:
> On Sat, Mar 11, 2017 at 10:02 PM, Jeff Jirsa
<jji...@gmail.com <mailto:jji...@gmail.com>> wrote:
> > On 2017-03-10 09:57 (-0800), Rakesh Kumar wrote:
> > > Cassanda vs Scylla is a valid comparison
because they both are
> > compatible. Scylla is a drop-in replacement
for Cassandra.
> >
> > No, they aren't, and no, it isn't
> >
>
> Jeff is angry with us for some reason. I don't
know why, it's natural that
> when a new opponent there are objections and
the proof lies on us.
I'm not angry. When I'm angry I send emails with
paragraphs of expletives. It doesn't happen very
often.
This is an open source ASF project, it's not about
fighting for market share against startups who
find it necessary to inflate their level of
compatibility to sell support contracts, it's
about providing software that people can use (with
a license that makes it easy to use). I don't work
for a company that makes money selling Cassandra
based solutions and you're not an opponent.
>
> Scylla IS a drop in replacement for C*. We
support the same CQL (from
> version 1.7 it's cql 3.3.1, protocol v4), the
same SStable format (based on
> 2.1.8).
Scylla doesn't even run on all of the supported
operating systems, let alone have feature parity
or network level compatibility (which you'd
probably need if you REALLY want to be drop-in
stop-one-cassandra-node-swap-binaries-start-it-up
compatible, which is what your site used to claim,
but obviously isn't supported). You support a
subset of one query language and can read and
write one sstable format. You do it with great
supporting tech and a great engineering team, but
you're not compatible, and if I were your
cofounder I'd ask you to focus on the tech
strengths and not your drop-in compatibility, so
engineers who care about facts don't grow to
resent your public lies.
I've used a lot of databases in my life, but I
don't know that I've ever had someone call me
angry because I pointed out that database A wasn't
compatible with database B, but I guess I'll chalk
it up to 2017 and the year of fake news /
alternative facts.
Hugs and kisses,
- Jeff
