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 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>, 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>, > "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. 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