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From Varun Sharma <va...@pinterest.com>
Subject Re: recommended nodes
Date Thu, 20 Dec 2012 21:37:55 GMT
Hmm, I thought that RAID0 simply stripes across all disks. So if you got 4
disks - an HFile block for example could get striped across 4 disks. So to
read that block, you would need all 4 of them to seek so that you could
read all 4 stripes for that HFile block. This could make things as slow as
the slowest seeking disk for that random read. However, certainly, data
xfer rate would be much faster with RAID0 but since this is merely 64K for
a HFile block, I would have expected the seek latency to play a major role
and not really the data xfer latency.

However, your tests indeed show that RAID0 still outperforms JBOD on seeks.
Am I missing something ?

On Thu, Dec 20, 2012 at 1:26 PM, Jean-Marc Spaggiari <
jean-marc@spaggiari.org> wrote:

> Hi Varun,
>
> The hard drivers I used are now used on the hadoop/hbase cluster, but they
> was clear and formated for the tests I did. The computer where I run those
> tests was one of the region servers. It was re-installed to be very clear,
> and it's now running a datanode and a RS.
>
> Regarding RAID, I think you are confusing RAID0 and RAID1. It's RAID1 which
> need to access the 2 files each time. RAID0 is more like JBOD, but faster.
>
> JM
>
> 2012/12/20 Varun Sharma <varun@pinterest.com>
>
> > Hi Jean,
> >
> > Very interesting benchmark - how are these numbers arrived at ? Is this
> on
> > a real hbase cluster ? To me, it felt kind of counter intuitive that
> RAID0
> > beats JBOD on random seeks because with RAID0 all disks need to seek at
> the
> > same time and the performance should basically be as bad as the slowest
> > seeking disk.
> >
> > Varun
> >
> > On Wed, Dec 19, 2012 at 5:14 PM, Michael Segel <
> michael_segel@hotmail.com
> > >wrote:
> >
> > > Yeah,
> > > I couldn't argue against LVMs when talking with the system admins.
> > > In terms of speed its noise because the CPUs are pretty efficient and
> > > unless you have more than 1 drive per physical core, you will end up
> > > saturating your disk I/O.
> > >
> > > In terms of MapR, you want the raw disk. (But we're talking Apache)
> > >
> > >
> > > On Dec 19, 2012, at 4:59 PM, Jean-Marc Spaggiari <
> > jean-marc@spaggiari.org>
> > > wrote:
> > >
> > > > Finally, it took me a while to run those tests because it was way
> > > > longer than expected, but here are the results:
> > > >
> > > > http://www.spaggiari.org/bonnie.html
> > > >
> > > > LVM is not really slower than JBOD and not really taking more CPU. So
> > > > I will say, if you have to choose between the 2, take the one you
> > > > prefer. Personally, I prefer LVM because it's easy to configure.
> > > >
> > > > The big winner here is RAID0. It's WAY faster than anything else. But
> > > > it's using twice the space... Your choice.
> > > >
> > > > I did not get a chance to test with the Ubuntu tool because it's not
> > > > working with LVM drives.
> > > >
> > > > JM
> > > >
> > > > 2012/11/28, Michael Segel <michael_segel@hotmail.com>:
> > > >> Ok, just a caveat.
> > > >>
> > > >> I am discussing MapR as part of a complete response. As Mohit posted
> > > MapR
> > > >> takes the raw device for their MapR File System.
> > > >> They do stripe on their own within what they call a volume.
> > > >>
> > > >> But going back to Apache...
> > > >> You can stripe drives, however I wouldn't recommend it. I don't
> think
> > > the
> > > >> performance gains would really matter.
> > > >> You're going to end up getting blocked first by disk i/o, then your
> > > >> controller card, then your network... assuming 10GBe.
> > > >>
> > > >> With only 2 disks on an 8 core system, you will hit disk i/o first
> and
> > > then
> > > >> you'll watch your CPU Wait I/O climb.
> > > >>
> > > >> HTH
> > > >>
> > > >> -Mike
> > > >>
> > > >> On Nov 28, 2012, at 7:28 PM, Jean-Marc Spaggiari <
> > > jean-marc@spaggiari.org>
> > > >> wrote:
> > > >>
> > > >>> Hi Mike,
> > > >>>
> > > >>> Why not using LVM with MapR? Since LVM is reading from 2 drives
> > almost
> > > >>> at the same time, it should be better than RAID0 or a single drive,
> > > >>> no?
> > > >>>
> > > >>> 2012/11/28, Michael Segel <michael_segel@hotmail.com>:
> > > >>>> Just a couple of things.
> > > >>>>
> > > >>>> I'm neutral on the use of LVMs. Some would point out that
there's
> > some
> > > >>>> overhead, but on the flip side, it can make managing the machines
> > > >>>> easier.
> > > >>>> If you're using MapR, you don't want to use LVMs but raw devices.
> > > >>>>
> > > >>>> In terms of GC, its going to depend on the heap size and not
the
> > total
> > > >>>> memory. With respect to HBase. ... MSLABS is the way to go.
> > > >>>>
> > > >>>>
> > > >>>> On Nov 28, 2012, at 12:05 PM, Jean-Marc Spaggiari
> > > >>>> <jean-marc@spaggiari.org>
> > > >>>> wrote:
> > > >>>>
> > > >>>>> Hi Gregory,
> > > >>>>>
> > > >>>>> I founs this about LVM:
> > > >>>>> -> http://blog.andrew.net.au/2006/08/09
> > > >>>>> ->
> > > >>>>>
> > > http://www.phoronix.com/scan.php?page=article&item=fedora_15_lvm&num=2
> > > >>>>>
> > > >>>>> Seems that performances are still correct with it. I will
most
> > > >>>>> probably give it a try and bench that too... I have one
new hard
> > > drive
> > > >>>>> which should arrived tomorrow. Perfect timing ;)
> > > >>>>>
> > > >>>>>
> > > >>>>>
> > > >>>>> JM
> > > >>>>>
> > > >>>>> 2012/11/28, Mohit Anchlia <mohitanchlia@gmail.com>:
> > > >>>>>>
> > > >>>>>>
> > > >>>>>>
> > > >>>>>>
> > > >>>>>> On Nov 28, 2012, at 9:07 AM, Adrien Mogenet <
> > > adrien.mogenet@gmail.com>
> > > >>>>>> wrote:
> > > >>>>>>
> > > >>>>>>> Does HBase really benefit from 64 GB of RAM since
allocating
> too
> > > >>>>>>> large
> > > >>>>>>> heap
> > > >>>>>>> might increase GC time ?
> > > >>>>>>>
> > > >>>>>> Benefit you get is from OS cache
> > > >>>>>>> Another question : why not RAID 0, in order to
aggregate disk
> > > >>>>>>> bandwidth
> > > >>>>>>> ?
> > > >>>>>>> (and thus keep 3x replication factor)
> > > >>>>>>>
> > > >>>>>>>
> > > >>>>>>> On Wed, Nov 28, 2012 at 5:58 PM, Michael Segel
> > > >>>>>>> <michael_segel@hotmail.com>wrote:
> > > >>>>>>>
> > > >>>>>>>> Sorry,
> > > >>>>>>>>
> > > >>>>>>>> I need to clarify.
> > > >>>>>>>>
> > > >>>>>>>> 4GB per physical core is a good starting point.
> > > >>>>>>>> So with 2 quad core chips, that is going to
be 32GB.
> > > >>>>>>>>
> > > >>>>>>>> IMHO that's a minimum. If you go with HBase,
you will want
> more.
> > > >>>>>>>> (Actually
> > > >>>>>>>> you will need more.) The next logical jump
would be to 48 or
> > 64GB.
> > > >>>>>>>>
> > > >>>>>>>> If we start to price out memory, depending
on vendor, your
> > > company's
> > > >>>>>>>> procurement,  there really isn't much of a
price difference in
> > > terms
> > > >>>>>>>> of
> > > >>>>>>>> 32,48, or 64 GB.
> > > >>>>>>>> Note that it also depends on the chips themselves.
Also you
> need
> > > to
> > > >>>>>>>> see
> > > >>>>>>>> how many memory channels exist in the mother
board. You may
> need
> > > to
> > > >>>>>>>> buy
> > > >>>>>>>> in
> > > >>>>>>>> pairs or triplets. Your hardware vendor can
help you. (Also
> you
> > > need
> > > >>>>>>>> to
> > > >>>>>>>> keep an eye on your hardware vendor. Sometimes
they will give
> > you
> > > >>>>>>>> higher
> > > >>>>>>>> density chips that are going to be more expensive...)
;-)
> > > >>>>>>>>
> > > >>>>>>>> I tend to like having extra memory from the
start.
> > > >>>>>>>> It gives you a bit more freedom and also protects
you from
> 'fat'
> > > >>>>>>>> code.
> > > >>>>>>>>
> > > >>>>>>>> Looking at YARN... you will need more memory
too.
> > > >>>>>>>>
> > > >>>>>>>>
> > > >>>>>>>> With respect to the hard drives...
> > > >>>>>>>>
> > > >>>>>>>> The best recommendation is to keep the drives
as JBOD and then
> > use
> > > >>>>>>>> 3x
> > > >>>>>>>> replication.
> > > >>>>>>>> In this case, make sure that the disk controller
cards can
> > handle
> > > >>>>>>>> JBOD.
> > > >>>>>>>> (Some don't support JBOD out of the box)
> > > >>>>>>>>
> > > >>>>>>>> With respect to RAID...
> > > >>>>>>>>
> > > >>>>>>>> If you are running MapR, no need for RAID.
> > > >>>>>>>> If you are running an Apache derivative, you
could use RAID 1.
> > > Then
> > > >>>>>>>> cut
> > > >>>>>>>> your replication to 2X. This makes it easier
to manage drive
> > > >>>>>>>> failures.
> > > >>>>>>>> (Its not the norm, but it works...) In some
clusters, they are
> > > using
> > > >>>>>>>> appliances like Net App's e series where the
machines see the
> > > drives
> > > >>>>>>>> as
> > > >>>>>>>> local attached storage and I think the appliances
themselves
> are
> > > >>>>>>>> using
> > > >>>>>>>> RAID.  I haven't played with this configuration,
however it
> > could
> > > >>>>>>>> make
> > > >>>>>>>> sense and its a valid design.
> > > >>>>>>>>
> > > >>>>>>>> HTH
> > > >>>>>>>>
> > > >>>>>>>> -Mike
> > > >>>>>>>>
> > > >>>>>>>> On Nov 28, 2012, at 10:33 AM, Jean-Marc Spaggiari
> > > >>>>>>>> <jean-marc@spaggiari.org>
> > > >>>>>>>> wrote:
> > > >>>>>>>>
> > > >>>>>>>>> Hi Mike,
> > > >>>>>>>>>
> > > >>>>>>>>> Thanks for all those details!
> > > >>>>>>>>>
> > > >>>>>>>>> So to simplify the equation, for 16 virtual
cores we need 48
> to
> > > >>>>>>>>> 64GB.
> > > >>>>>>>>> Which mean 3 to 4GB per core. So with
quad cores, 12GB to
> 16GB
> > > are
> > > >>>>>>>>> a
> > > >>>>>>>>> good start? Or I simplified it to much?
> > > >>>>>>>>>
> > > >>>>>>>>> Regarding the hard drives. If you add
more than one drive, do
> > you
> > > >>>>>>>>> need
> > > >>>>>>>>> to build them on RAID or similar systems?
Or can Hadoop/HBase
> > be
> > > >>>>>>>>> configured to use more than one drive?
> > > >>>>>>>>>
> > > >>>>>>>>> Thanks,
> > > >>>>>>>>>
> > > >>>>>>>>> JM
> > > >>>>>>>>>
> > > >>>>>>>>> 2012/11/27, Michael Segel <michael_segel@hotmail.com>:
> > > >>>>>>>>>>
> > > >>>>>>>>>> OK... I don't know why Cloudera is
so hung up on 32GB. ;-)
> > [Its
> > > an
> > > >>>>>>>> inside
> > > >>>>>>>>>> joke ...]
> > > >>>>>>>>>>
> > > >>>>>>>>>> So here's the problem...
> > > >>>>>>>>>>
> > > >>>>>>>>>> By default, your child processes in
a map/reduce job get a
> > > default
> > > >>>>>>>> 512MB.
> > > >>>>>>>>>> The majority of the time, this gets
raised to 1GB.
> > > >>>>>>>>>>
> > > >>>>>>>>>> 8 cores (dual quad cores) shows up
at 16 virtual processors
> in
> > > >>>>>>>>>> Linux.
> > > >>>>>>>> (Note:
> > > >>>>>>>>>> This is why when people talk about
the number of cores, you
> > have
> > > >>>>>>>>>> to
> > > >>>>>>>> specify
> > > >>>>>>>>>> physical cores or logical cores....)
> > > >>>>>>>>>>
> > > >>>>>>>>>> So if you were to over subscribe and
have lets say 12
>  mappers
> > > and
> > > >>>>>>>>>> 12
> > > >>>>>>>>>> reducers, that's 24 slots. Which means
that you would need
> > 24GB
> > > of
> > > >>>>>>>> memory
> > > >>>>>>>>>> reserved just for the child processes.
This would leave 8GB
> > for
> > > >>>>>>>>>> DN,
> > > >>>>>>>>>> TT
> > > >>>>>>>> and
> > > >>>>>>>>>> the rest of the linux OS processes.
> > > >>>>>>>>>>
> > > >>>>>>>>>> Can you live with that? Sure.
> > > >>>>>>>>>> Now add in R, HBase, Impala, or some
other set of tools on
> top
> > > of
> > > >>>>>>>>>> the
> > > >>>>>>>>>> cluster.
> > > >>>>>>>>>>
> > > >>>>>>>>>> Ooops! Now you are in trouble because
you will swap.
> > > >>>>>>>>>> Also adding in R, you may want to
bump up those child procs
> > from
> > > >>>>>>>>>> 1GB
> > > >>>>>>>>>> to
> > > >>>>>>>> 2
> > > >>>>>>>>>> GB. That means the 24 slots would
now require 48GB.  Now you
> > > have
> > > >>>>>>>>>> swap
> > > >>>>>>>> and
> > > >>>>>>>>>> if that happens you will see HBase
in a cascading failure.
> > > >>>>>>>>>>
> > > >>>>>>>>>> So while you can do a rolling restart
with the changed
> > > >>>>>>>>>> configuration
> > > >>>>>>>>>> (reducing the number of mappers and
reducers) you end up
> with
> > > less
> > > >>>>>>>>>> slots
> > > >>>>>>>>>> which will mean in longer run time
for your jobs. (Less
> slots
> > ==
> > > >>>>>>>>>> less
> > > >>>>>>>>>> parallelism )
> > > >>>>>>>>>>
> > > >>>>>>>>>> Looking at the price of memory...
you can get 48GB or even
> > 64GB
> > > >>>>>>>>>> for
> > > >>>>>>>> around
> > > >>>>>>>>>> the same price point. (8GB chips)
> > > >>>>>>>>>>
> > > >>>>>>>>>> And I didn't even talk about adding
SOLR either again a
> memory
> > > >>>>>>>>>> hog...
> > > >>>>>>>> ;-)
> > > >>>>>>>>>>
> > > >>>>>>>>>> Note that I matched the number of
mappers w reducers. You
> > could
> > > go
> > > >>>>>>>>>> with
> > > >>>>>>>>>> fewer reducers if you want. I tend
to recommend a ratio of
> 2:1
> > > >>>>>>>>>> mappers
> > > >>>>>>>> to
> > > >>>>>>>>>> reducers, depending on the work flow....
> > > >>>>>>>>>>
> > > >>>>>>>>>> As to the disks... no 7200 SATA III
drives are fine. SATA
> III
> > > >>>>>>>>>> interface
> > > >>>>>>>> is
> > > >>>>>>>>>> pretty much available in the new kit
being shipped.
> > > >>>>>>>>>> Its just that you don't have enough
drives. 8 cores should
> be
> > 8
> > > >>>>>>>> spindles if
> > > >>>>>>>>>> available.
> > > >>>>>>>>>> Otherwise you end up seeing your CPU
load climb on wait
> states
> > > as
> > > >>>>>>>>>> the
> > > >>>>>>>>>> processes wait for the disk i/o to
catch up.
> > > >>>>>>>>>>
> > > >>>>>>>>>> I mean you could build out a cluster
w 4 x 3 3.5" 2TB drives
> > in
> > > a
> > > >>>>>>>>>> 1
> > > >>>>>>>>>> U
> > > >>>>>>>>>> chassis based on price. You're making
a trade off and you
> > should
> > > >>>>>>>>>> be
> > > >>>>>>>> aware of
> > > >>>>>>>>>> the performance hit you will take.
> > > >>>>>>>>>>
> > > >>>>>>>>>> HTH
> > > >>>>>>>>>>
> > > >>>>>>>>>> -Mike
> > > >>>>>>>>>>
> > > >>>>>>>>>> On Nov 27, 2012, at 1:52 PM, Jean-Marc
Spaggiari <
> > > >>>>>>>> jean-marc@spaggiari.org>
> > > >>>>>>>>>> wrote:
> > > >>>>>>>>>>
> > > >>>>>>>>>>> Hi Michael,
> > > >>>>>>>>>>>
> > > >>>>>>>>>>> so are you recommanding 32Gb per
node?
> > > >>>>>>>>>>>
> > > >>>>>>>>>>> What about the disks? SATA drives
are to slow?
> > > >>>>>>>>>>>
> > > >>>>>>>>>>> JM
> > > >>>>>>>>>>>
> > > >>>>>>>>>>> 2012/11/26, Michael Segel <michael_segel@hotmail.com>:
> > > >>>>>>>>>>>> Uhm, those specs are actually
now out of date.
> > > >>>>>>>>>>>>
> > > >>>>>>>>>>>> If you're running HBase, or
want to also run R on top of
> > > Hadoop,
> > > >>>>>>>>>>>> you
> > > >>>>>>>>>>>> will
> > > >>>>>>>>>>>> need to add more memory.
> > > >>>>>>>>>>>> Also forget 1GBe got 10GBe,
 and w 2 SATA drives, you will
> > be
> > > >>>>>>>>>>>> disk
> > > >>>>>>>>>>>> i/o
> > > >>>>>>>>>>>> bound
> > > >>>>>>>>>>>> way too quickly.
> > > >>>>>>>>>>>>
> > > >>>>>>>>>>>>
> > > >>>>>>>>>>>> On Nov 26, 2012, at 8:05 AM,
Marcos Ortiz <mlortiz@uci.cu
> >
> > > >>>>>>>>>>>> wrote:
> > > >>>>>>>>>>>>
> > > >>>>>>>>>>>>> Are you asking about hardware
recommendations?
> > > >>>>>>>>>>>>> Eric Sammer on his "Hadoop
Operations" book, did a great
> > job
> > > >>>>>>>>>>>>> about
> > > >>>>>>>>>>>>> this:
> > > >>>>>>>>>>>>> For middle size clusters
(until 300 nodes):
> > > >>>>>>>>>>>>> Processor: A dual quad-core
2.6 Ghz
> > > >>>>>>>>>>>>> RAM: 24 GB DDR3
> > > >>>>>>>>>>>>> Dual 1 Gb Ethernet NICs
> > > >>>>>>>>>>>>> a SAS drive controller
> > > >>>>>>>>>>>>> at least two SATA II drives
in a JBOD configuration
> > > >>>>>>>>>>>>>
> > > >>>>>>>>>>>>> The replication factor
depends heavily of the primary use
> > of
> > > >>>>>>>>>>>>> your
> > > >>>>>>>>>>>>> cluster.
> > > >>>>>>>>>>>>>
> > > >>>>>>>>>>>>> On 11/26/2012 08:53 AM,
David Charle wrote:
> > > >>>>>>>>>>>>>> hi
> > > >>>>>>>>>>>>>>
> > > >>>>>>>>>>>>>> what's the recommended
nodes for NN, hmaster and zk
> nodes
> > > for
> > > >>>>>>>>>>>>>> a
> > > >>>>>>>> larger
> > > >>>>>>>>>>>>>> cluster, lets say
50-100+
> > > >>>>>>>>>>>>>>
> > > >>>>>>>>>>>>>> also, what would be
the ideal replication factor for
> > larger
> > > >>>>>>>>>>>>>> clusters
> > > >>>>>>>>>>>>>> when
> > > >>>>>>>>>>>>>> u have 3-4 racks ?
> > > >>>>>>>>>>>>>>
> > > >>>>>>>>>>>>>> --
> > > >>>>>>>>>>>>>> David
> > > >>>>>>>>>>>>>> 10mo. ANIVERSARIO
DE LA CREACION DE LA UNIVERSIDAD DE
> LAS
> > > >>>>>>>>>>>>>> CIENCIAS
> > > >>>>>>>>>>>>>> INFORMATICAS...
> > > >>>>>>>>>>>>>> CONECTADOS AL FUTURO,
CONECTADOS A LA REVOLUCION
> > > >>>>>>>>>>>>>>
> > > >>>>>>>>>>>>>> http://www.uci.cu
> > > >>>>>>>>>>>>>> http://www.facebook.com/universidad.uci
> > > >>>>>>>>>>>>>> http://www.flickr.com/photos/universidad_uci
> > > >>>>>>>>>>>>>
> > > >>>>>>>>>>>>> --
> > > >>>>>>>>>>>>>
> > > >>>>>>>>>>>>> Marcos Luis Ortíz Valmaseda
> > > >>>>>>>>>>>>> about.me/marcosortiz <http://about.me/marcosortiz>
> > > >>>>>>>>>>>>> @marcosluis2186 <http://twitter.com/marcosluis2186>
> > > >>>>>>>>>>>>>
> > > >>>>>>>>>>>>>
> > > >>>>>>>>>>>>>
> > > >>>>>>>>>>>>> 10mo. ANIVERSARIO DE LA
CREACION DE LA UNIVERSIDAD DE LAS
> > > >>>>>>>>>>>>> CIENCIAS
> > > >>>>>>>>>>>>> INFORMATICAS...
> > > >>>>>>>>>>>>> CONECTADOS AL FUTURO,
CONECTADOS A LA REVOLUCION
> > > >>>>>>>>>>>>>
> > > >>>>>>>>>>>>> http://www.uci.cu
> > > >>>>>>>>>>>>> http://www.facebook.com/universidad.uci
> > > >>>>>>>>>>>>> http://www.flickr.com/photos/universidad_uci
> > > >>>>>>>
> > > >>>>>>>
> > > >>>>>>> --
> > > >>>>>>> Adrien Mogenet
> > > >>>>>>> 06.59.16.64.22
> > > >>>>>>> http://www.mogenet.me
> > > >>>>>>
> > > >>>>>
> > > >>>>
> > > >>>>
> > > >>>
> > > >>
> > > >>
> > > >
> > >
> > >
> >
>

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