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From lars hofhansl <la...@apache.org>
Subject Re: Cluster sizing guidelines
Date Sat, 19 Jul 2014 08:24:12 GMT
We can answer #3 at least: You can store about 2T of effective data per node in HBase, unless
you have a mostly read-only load.
See here for the reasoning: http://hadoop-hbase.blogspot.de/2013/01/hbase-region-server-memory-sizing.html

For #1 we were traditionally bound by disk/network IO (due to the 2-way replication). With
SSDs and 10ge networks that is no longer true, though.

As Andy said, #1 and #2 depend heavily on your setup, and there a quite a few tuning knobs
for particular setups.

We did some throughput tests with our setup. I'll see whether we can get those published.
But note that these are valid only for our particular setup and network topology and our workloads,
and are likely not generally useful.


Also, HBase is a row store. The number of rows or KeyValues per unit of data will also strongly
influence the performance, there is a per KeyValue cost and even a per row cost for both read
and write throughput. It also depends on how many parallel clients you use, as HBase currently
does not stream data between client/server and server/server and hence cannot keep the network
pipes full unless multiple clients are used.


So it might be hard to present such metrics as a 2D graph.

-- Lars



________________________________
 From: Andrew Purtell <apurtell@apache.org>
To: "user@hbase.apache.org" <user@hbase.apache.org> 
Sent: Wednesday, July 16, 2014 2:32 PM
Subject: Re: Cluster sizing guidelines
 

Those questions don't have pat answers. HBase has a few interesting load
dependent tunables and the ceiling you'll encounter depends as much on the
characteristics of the nodes (particularly, block devices) and the network,
not merely the software.

We can certainly, through experimentation, establish upper bounds on perf,
optimizing either for throughput at a given payload size or latency within
a given bound (your questions #1 and #2). I. e. using now-typical systems
with 32 cores, 64-128 GB of RAM (and a fair amount allocated to bucket
cache), and 2-4 solid state volumes, and a 10ge network, here are plots of
the measured upper bound of metric M on the y-axis over number of slave
cluster nodes on the X axis.

Open questions:
1. Which measurement tool and test automation?
2. Where can we get ~100 decent nodes for a realistic assessment?
3. Who's going to fund the test dev and testbed?




On Wed, Jul 16, 2014 at 1:41 PM, Amandeep Khurana <amansk@gmail.com> wrote:

> Thanks Lars.
>
> I'm curious how we'd answer questions like:
> 1. How many nodes do I need to sustain a write throughput of N reqs/sec
> with payload of size M KB?
> 2. How many nodes do I need to sustain a read throughput of N reqs/sec with
> payload of size M KB with a latency of X ms per read.
> 3. How many nodes do I need to store N TB of total data with one of the
> above constraints?
>
> This goes into looking at the bottlenecks that need to be taken into
> account during write and read times and also the max number of regions and
> region size that a single region server can host.
>
> What are your thoughts on this?
>
> -Amandeep
>
>
> On Wed, Jul 16, 2014 at 9:06 AM, lars hofhansl <larsh@apache.org> wrote:
>
> > This is a somewhat fuzzy art.
> >
> > Some points to consider:
> > 1. All data is replicated three ways. Or in other words, if you run three
> > RegionServer/Datanodes each machine will get 100% of the writes. If you
> run
> > 6, each gets 50% of the writes. From that aspect HBase clusters with less
> > than 9 RegionServers are not really useful.
> > 2. As for the machines themselves. Just go with any reasonable machine,
> > and pick the cheapest you can find. At least 8 cores, at least 32GB of
> RAM,
> > at least 6 disks, no RAID needed. (we have machines with 12 cores in 2
> > sockets, 96GB of RAM, 6 4TB drives, no HW RAID). HBase is not yet well
> > tuned for SSDs.
> >
> >
> > You also carefully need to consider your network topology. With HBase
> > you'll see quite some east-west traffic (i.e. between racks). 10ge is
> good
> > if you have it. We have 1ge everywhere so far, and we found this is a
> > single most bottleneck for write performance.
> >
> >
> > Also see this blog post about HBase memory sizing (shameless plug):
> >
> http://hadoop-hbase.blogspot.de/2013/01/hbase-region-server-memory-sizing.html
> >
> >
> > I'm planning a blog post about this topic with more details.
> >
> >
> > -- Lars
> >
> >
> >
> > ________________________________
> >  From: Amandeep Khurana <amansk@gmail.com>
> > To: "user@hbase.apache.org" <user@hbase.apache.org>
> > Sent: Tuesday, July 15, 2014 10:48 PM
> > Subject: Cluster sizing guidelines
> >
> >
> > Hi
> >
> > How do users usually go about sizing HBase clusters? What are the factors
> > you take into account? What are typical hardware profiles you run with?
> Any
> > data points you can share would help.
> >
> > Thanks
> > Amandeep
> >
>



-- 
Best regards,

   - Andy

Problems worthy of attack prove their worth by hitting back. - Piet Hein
(via Tom White)
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