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From Jeff Jirsa <>
Subject Re: EC2 storage options for C*
Date Sun, 31 Jan 2016 08:13:38 GMT
Hi John,

We run using 4T GP2 volumes, which guarantee 10k iops. Even at 1M writes per second on 60
nodes, we didn’t come close to hitting even 50% utilization (10k is more than enough for
most workloads). PIOPS is not necessary. 

From:  John Wong
Reply-To:  ""
Date:  Saturday, January 30, 2016 at 3:07 PM
To:  ""
Subject:  Re: EC2 storage options for C*

For production I'd stick with ephemeral disks (aka instance storage) if you have running a
lot of transaction. 
However, for regular small testing/qa cluster, or something you know you want to reload often,
EBS is definitely good enough and we haven't had issues 99%. The 1% is kind of anomaly where
we have flush blocked.

But Jeff, kudo that you are able to use EBS. I didn't go through the video, do you actually
use PIOPS or just standard GP2 in your production cluster?

On Sat, Jan 30, 2016 at 1:28 PM, Bryan Cheng <> wrote:
Yep, that motivated my question "Do you have any idea what kind of disk performance you need?".
If you need the performance, its hard to beat ephemeral SSD in RAID 0 on EC2, and its a solid,
battle tested configuration. If you don't, though, EBS GP2 will save a _lot_ of headache.

Personally, on small clusters like ours (12 nodes), we've found our choice of instance dictated
much more by the balance of price, CPU, and memory. We're using GP2 SSD and we find that for
our patterns the disk is rarely the bottleneck. YMMV, of course.

On Fri, Jan 29, 2016 at 7:32 PM, Jeff Jirsa <> wrote:
If you have to ask that question, I strongly recommend m4 or c4 instances with GP2 EBS.  When
you don’t care about replacing a node because of an instance failure, go with i2+ephemerals.
Until then, GP2 EBS is capable of amazing things, and greatly simplifies life.

We gave a talk on this topic at both Cassandra Summit and AWS re:Invent:
It’s very much a viable option, despite any old documents online that say otherwise.

From: Eric Plowe
Reply-To: ""
Date: Friday, January 29, 2016 at 4:33 PM
To: ""
Subject: EC2 storage options for C*

My company is planning on rolling out a C* cluster in EC2. We are thinking about going with
ephemeral SSDs. The question is this: Should we put two in RAID 0 or just go with one? We
currently run a cluster in our data center with 2 250gig Samsung 850 EVO's in RAID 0 and we
are happy with the performance we are seeing thus far.



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