EBS performance was a major concern a few years ago, but it's gotten better in the last few years with things like Provisioned IOPS and SSDs. However, it's still not recommended (reasons outlined here <http://www.datastax.com/documentation/cassandra/2.0/cassandra/architecture/architecturePlanningEC2_c.html> .)
I personally don't care for EBS because of the reliability factor. Do a web search for EBS outage and you'll see that EBS has caused much pain for lots of organizations in the past. Ephemeral disks (which exist on the host of which your instance is running) will always be more reliable and generally are more performant. The trend seems to be that they're pushing people towards EBS (t2 instances are EBS only, other current gen instances are SSD only) and it's a shame. It's good to have choices. -Jared On 5 September 2014 13:51, William Oberman <ober...@civicscience.com> wrote: > Theory aside, I switched from "RAID of ephemerals" for data, and root > volume for write log to single EBS-based SSD without any noticeable impact > on performance. > > will > > On Thu, Sep 4, 2014 at 9:35 PM, Steve Robenalt <sroben...@highwire.org> > wrote: > >> Yes, I am aware there are no heads on an SSD. I also have seen plenty of >> examples where compatibility issues force awkward engineering tradeoffs, >> even as technology advances so I am jaded enough to be wary of making >> assumptions, which is why I asked the question. >> >> Steve >> On Sep 4, 2014 5:50 PM, "Robert Coli" <rc...@eventbrite.com> wrote: >> >>> On Thu, Sep 4, 2014 at 5:44 PM, Steve Robenalt <sroben...@highwire.org> >>> wrote: >>> >>>> Thanks Robert! I am assuming that you meant that it's possible with a >>>> single SSD, right? >>>> >>> >>> Yes, no matter how many SSDs you have you are unlikely to be able to >>> convince one of them to physically seek a drive head across its plater, >>> because they don't have heads or platters. >>> >>> =Rob >>> >> > > >
