Hi Jörg,
I'm the author of those slides, and that statement, even when taken out of
context starts with "Prefer",
I don't think I need to explain what prefer means, but just in case ...
Using JBOD will be your safest bet as opposed to using something like RAID
/ SAN/ NAS unless you really know what you're doing.
I never said DON'T EVER use RAID or even SAN|NAS, just "prefer" JBOD.
I do agree with your assessment of RAID 0 below, but do remember that, that
one statement was taken out of context, for full context I suggest you go
through the whole slide deck and better yet the whole talk whose video was
posted on elasticsearch site. I even made a point about some of my
recommendations not being applicable to cloud deployments etc.
As to your point about simplification of NAS|SAN, that's the whole point of
presenting to a wide audience, one simplifies things such that they can be
applied to majority of the cases, and not concentrate on esoteric
deployments :). As to local gateway, that's the only one ES recommends now,
the shared FS, HDFS, S3 gateways were long deprecated.
FWIW I fully agree with your statement on taking control over complete
hardware setup, heck there's a full slide in there dedicated to this point,
titled 'Know your platform'.
At the end of the day, there's no single silver bullet, everyone will have
to evaluate what works best for their situation, what worked for us may not
work well for others. It would be indeed very naive to take my slides as
laws, they are more or less pointers worth exploring. Some may work for you
some won't. They worked fairly well for us.
I might sound a bit defensive here, but hey we did build that cluster and
we're nearing a Trillion documents in it, so I guess we must be doing
something right :).
Bhaskar
On Saturday, December 13, 2014 at 10:48:55 AM UTC-5, Jörg Prante wrote:
The statement is related to performance and I can't agree with it. You can
easily build a RAID 0 system which has massive I/O throughput performance
and is superior to JBOD, because RAID striping does not slow things down,
it is as always as much as fast than a single drive and in most RAID levels
it is much faster.
In the past, RAID was invented for mirroring cheap and error-prone spindle
disk arrays, while mirrors increase costs but decrease fault probability.
With Elasticsearch, the decision is if you still want to handle disk
faults by drive redundancy (RAID) and all other hardware faults like power
outages by server downtime. This is just a matter of organization and of
cost. I would suggest from my experience: take control over your complete
hardware setup, equip your systems with expensive SAS2 (or even better)
controllers with RAID 0 to reduce cost and maximize performance, and handle
all kind of hardware faults by server downtime, because ES replica level >
0 allows that.
There is also a simplification of SAN/NAS in the statement but that is a
different discussion. Never use SAN/NAS for ES local gateway.
Jörg
On Fri, Dec 12, 2014 at 7:28 PM, Elvar Böðvarsson <elv...@gmail.com
<javascript:>> wrote:
Second, "Prefer JBODs for data disks over RAID, SAN/NAS", would be ok,
maybe then to be safe go with 2x replicas, goes well with having 3x nodes
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