By that do you mean it’s like bootstrapping a node if it fails or is shutdown 
and with a RF that is 2 or higher, data will get replicated when it’s brought 
up?

From: Cogumelos Maravilha <cogumelosmaravi...@sapo.pt>
Date: Tuesday, May 23, 2017 at 1:52 PM
To: "user@cassandra.apache.org" <user@cassandra.apache.org>
Subject: Re: EC2 instance recommendations


Yes we can only reboot.

But using rf=2 or higher it's only a node fresh restart.

EBS is a network attached disk. Spinning disk or SSD is almost the same.

It's better take the "risk" and use type i instances.

Cheers.

On 23-05-2017 21:39, sfesc...@gmail.com<mailto:sfesc...@gmail.com> wrote:
I think this is overstating it. If the instance ever stops you'll lose the 
data. That means if the server crashes for example, or if Amazon decides your 
instance requires maintenance.

On Tue, May 23, 2017 at 10:30 AM Gopal, Dhruva 
<dhruva.go...@aspect.com<mailto:dhruva.go...@aspect.com>> wrote:
Thanks! So, I assume that as long we make sure we never explicitly “shutdown” 
the instance, we are good. Are you also saying we won’t be able to snapshot a 
directory with ephemeral storage and that is why EBS is better? We’re just 
finding that to get a reasonable amount of IOPS (gp2) out of EBS at a 
reasonable rate, it gets more expensive than an I3.

From: Jonathan Haddad <j...@jonhaddad.com<mailto:j...@jonhaddad.com>>
Date: Tuesday, May 23, 2017 at 9:42 AM
To: "Gopal, Dhruva" <dhruva.go...@aspect.com><mailto:dhruva.go...@aspect.com>, 
Matija Gobec <matija0...@gmail.com<mailto:matija0...@gmail.com>>, Bhuvan Rawal 
<bhu1ra...@gmail.com<mailto:bhu1ra...@gmail.com>>
Cc: "user@cassandra.apache.org<mailto:user@cassandra.apache.org>" 
<user@cassandra.apache.org<mailto:user@cassandra.apache.org>>

Subject: Re: EC2 instance recommendations

> Oh, so all the data is lost if the instance is shutdown or restarted (for 
> that instance)?

When you restart the OS, you're technically not shutting down the instance.  As 
long as the instance isn't stopped / terminated, your data is fine.  I ran my 
databases on ephemeral storage for years without issue.  In general, ephemeral 
storage is going to give you lower latency since there's no network overhead.  
EBS is generally cheaper than ephemeral, is persistent, and you can take 
snapshots easily.

On Tue, May 23, 2017 at 9:35 AM Gopal, Dhruva 
<dhruva.go...@aspect.com<mailto:dhruva.go...@aspect.com>> wrote:
Oh, so all the data is lost if the instance is shutdown or restarted (for that 
instance)? If we take a naïve approach to backing up the directory, and 
restoring it, if we ever have to bring down the instance and back up, will that 
work as a strategy? Data is only kept around for 2 days and is TTL’d after.

From: Matija Gobec <matija0...@gmail.com<mailto:matija0...@gmail.com>>
Date: Tuesday, May 23, 2017 at 8:15 AM
To: Bhuvan Rawal <bhu1ra...@gmail.com<mailto:bhu1ra...@gmail.com>>
Cc: "Gopal, Dhruva" <dhruva.go...@aspect.com><mailto:dhruva.go...@aspect.com>, 
"user@cassandra.apache.org<mailto:user@cassandra.apache.org>" 
<user@cassandra.apache.org<mailto:user@cassandra.apache.org>>
Subject: Re: EC2 instance recommendations

We are running on I3s since they came out. NVMe SSDs are really fast and I 
managed to push them to 75k IOPs.
As Bhuvan mentioned the i3 storage is ephemeral. If you can work around it and 
plan for failure recovery you are good to go.

I ran Cassandra on m4s before and had no problems with EBS volumes (gp2) even 
in low latency use cases. With the cost of M4 instances and EBS volumes that 
make sense in IOPs, I would recommend going with more i3s and working around 
the ephemeral issue (if its an issue).

Best,
Matija
On Tue, May 23, 2017 at 2:13 AM, Bhuvan Rawal 
<bhu1ra...@gmail.com<mailto:bhu1ra...@gmail.com>> wrote:
i3 instances will undoubtedly give you more meat for buck - easily 40K+ iops 
whereas on the other hand EBS maxes out at 20K PIOPS which is highly expensive 
(at times they can cost you significantly more than cost of instance).
But they have ephemeral local storage and data is lost once instance is 
stopped, you need to be prudent in case of i series, it is generally used for 
large persistent caches.

Regards,
Bhuvan
On Tue, May 23, 2017 at 4:55 AM, Gopal, Dhruva 
<dhruva.go...@aspect.com<mailto:dhruva.go...@aspect.com>> wrote:
Hi –
  We’ve been running M4.2xlarge EC2 instances with 2-3 TB of storage and have 
been comparing this to I-3.2xlarge, which seems more cost effective when 
dealing with this amount of storage and from an IOPS perspective. Does anyone 
have any recommendations/ on the I-3s and how it performs overall, compared to 
the M4 equivalent? On the surface, without us having taken it through its paces 
performance-wise, it does seem to be pretty powerful. We just ran through an 
exercise with a RAIDed 200 TB volume (as opposed to a non RAIDed 3 TB volume) 
and were seeing a 20-30% improvement with the RAIDed setup, on a 6 node 
Cassandra ring. Just looking for any feedback/experience folks may have had 
with the I-3s.

Regards,
DHRUVA GOPAL
sr. MANAGER, ENGINEERING
REPORTING, ANALYTICS AND BIG DATA
+1 408.325.2011<tel:+1%20408-325-2011> WORK
+1 408.219.1094<tel:+1%20408-219-1094> MOBILE
UNITED STATES
dhruva.go...@aspect.com<mailto:dhruva.go...@aspect.com>
aspect.com<http://www.aspect.com/>
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