hadoop-mapreduce-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Ted Dunning <tdunn...@maprtech.com>
Subject Re: Estimating disk space requirements
Date Fri, 18 Jan 2013 23:36:30 GMT
If you make 20 individual small servers, that isn't much different from 20
from one server.  The only difference would be if the neighbors of the
separate VMs use less resource.

On Fri, Jan 18, 2013 at 3:34 PM, Panshul Whisper <ouchwhisper@gmail.com>wrote:

> ah now i understand what you mean.
> I will be creating 20 individual servers on the cloud, and not create one
> big server and make several virtual nodes inside it.
> I will be paying for 20 different nodes.. all configured with hadoop and
> connected to the cluster.
>
> Thanx for the intel :)
>
>
> On Fri, Jan 18, 2013 at 11:59 PM, Ted Dunning <tdunning@maprtech.com>wrote:
>
>> It is usually better to not subdivide nodes into virtual nodes.  You will
>> generally get better performance form the original node because you only
>> pay for the OS once and because your disk I/O will be scheduled better.
>>
>> If you look at EC2 pricing, however, the spot market often has arbitrage
>> opportunities where one size node is absurdly cheap relative to others.  In
>> that case, it pays to scale the individual nodes up or down.
>>
>> The only reasonable reason to split nodes to very small levels is for
>> testing and training.
>>
>>
>> On Fri, Jan 18, 2013 at 2:30 PM, Panshul Whisper <ouchwhisper@gmail.com>wrote:
>>
>>> Thnx for the reply Ted,
>>>
>>> You can find 40 GB disks when u make virtual nodes on a cloud like
>>> Rackspace ;-)
>>>
>>> About the os partitions I did not exactly understand what you meant.
>>> I have made a server on the cloud.. And I just installed and configured
>>> hadoop and hbase in the /use/local folder.
>>> And I am pretty sure it does not have a separate partition for root.
>>>
>>> Please help me explain what u meant and what else precautions should I
>>> take.
>>>
>>> Thanks,
>>>
>>> Regards,
>>> Ouch Whisper
>>> 01010101010
>>> On Jan 18, 2013 11:11 PM, "Ted Dunning" <tdunning@maprtech.com> wrote:
>>>
>>>> Where do you find 40gb disks now a days?
>>>>
>>>> Normally your performance is going to be better with more space but
>>>> your network may be your limiting factor for some computations.  That could
>>>> give you some paradoxical scaling.  Hbase will rarely show this behavior.
>>>>
>>>> Keep in mind you also want to allow for an os partition. Current
>>>> standard practice is to reserve as much as 100 GB for that partition but
in
>>>> your case 10gb better:-)
>>>>
>>>> Note that if you account for this, the node counts don't scale as
>>>> simply.  The overhead of these os partitions goes up with number of nodes.
>>>>
>>>> On Jan 18, 2013, at 8:55 AM, Panshul Whisper <ouchwhisper@gmail.com>
>>>> wrote:
>>>>
>>>> If we look at it with performance in mind,
>>>> is it better to have 20 Nodes with 40 GB HDD
>>>> or is it better to have 10 Nodes with 80 GB HDD?
>>>>
>>>> they are connected on a gigabit LAN
>>>>
>>>> Thnx
>>>>
>>>>
>>>> On Fri, Jan 18, 2013 at 2:26 PM, Jean-Marc Spaggiari <
>>>> jean-marc@spaggiari.org> wrote:
>>>>
>>>>> 20 nodes with 40 GB will do the work.
>>>>>
>>>>> After that you will have to consider performances based on your access
>>>>> pattern. But that's another story.
>>>>>
>>>>> JM
>>>>>
>>>>> 2013/1/18, Panshul Whisper <ouchwhisper@gmail.com>:
>>>>> > Thank you for the replies,
>>>>> >
>>>>> > So I take it that I should have atleast 800 GB on total free space
on
>>>>> > HDFS.. (combined free space of all the nodes connected to the
>>>>> cluster). So
>>>>> > I can connect 20 nodes having 40 GB of hdd on each node to my
>>>>> cluster. Will
>>>>> > this be enough for the storage?
>>>>> > Please confirm.
>>>>> >
>>>>> > Thanking You,
>>>>> > Regards,
>>>>> > Panshul.
>>>>> >
>>>>> >
>>>>> > On Fri, Jan 18, 2013 at 1:36 PM, Jean-Marc Spaggiari <
>>>>> > jean-marc@spaggiari.org> wrote:
>>>>> >
>>>>> >> Hi Panshul,
>>>>> >>
>>>>> >> If you have 20 GB with a replication factor set to 3, you have
only
>>>>> >> 6.6GB available, not 11GB. You need to divide the total space
by the
>>>>> >> replication factor.
>>>>> >>
>>>>> >> Also, if you store your JSon into HBase, you need to add the
key
>>>>> size
>>>>> >> to it. If you key is 4 bytes, or 1024 bytes, it makes a difference.
>>>>> >>
>>>>> >> So roughly, 24 000 000 * 5 * 1024 = 114GB. You don't have the
space
>>>>> to
>>>>> >> store it. Without including the key size. Even with a replication
>>>>> >> factor set to 5 you don't have the space.
>>>>> >>
>>>>> >> Now, you can add some compression, but even with a lucky factor
of
>>>>> 50%
>>>>> >> you still don't have the space. You will need something like
90%
>>>>> >> compression factor to be able to store this data in your cluster.
>>>>> >>
>>>>> >> A 1T drive is now less than $100... So you might think about
>>>>> replacing
>>>>> >> you 20 GB drives by something bigger.
>>>>> >> to reply to your last question, for your data here, you will
need AT
>>>>> >> LEAST 350GB overall storage. But that's a bare minimum. Don't
go
>>>>> under
>>>>> >> 500GB.
>>>>> >>
>>>>> >> IMHO
>>>>> >>
>>>>> >> JM
>>>>> >>
>>>>> >> 2013/1/18, Panshul Whisper <ouchwhisper@gmail.com>:
>>>>> >> > Hello,
>>>>> >> >
>>>>> >> > I was estimating how much disk space do I need for my cluster.
>>>>> >> >
>>>>> >> > I have 24 million JSON documents approx. 5kb each
>>>>> >> > the Json is to be stored into HBASE with some identifying
data in
>>>>> >> coloumns
>>>>> >> > and I also want to store the Json for later retrieval based
on
>>>>> the Id
>>>>> >> data
>>>>> >> > as keys in Hbase.
>>>>> >> > I have my HDFS replication set to 3
>>>>> >> > each node has Hadoop and hbase and Ubuntu installed on
it.. so
>>>>> approx
>>>>> >> > 11
>>>>> >> GB
>>>>> >> > is available for use on my 20 GB node.
>>>>> >> >
>>>>> >> > I have no idea, if I have not enabled Hbase replication,
is the
>>>>> HDFS
>>>>> >> > replication enough to keep the data safe and redundant.
>>>>> >> > How much total disk space I will need for the storage of
the data.
>>>>> >> >
>>>>> >> > Please help me estimate this.
>>>>> >> >
>>>>> >> > Thank you so much.
>>>>> >> >
>>>>> >> > --
>>>>> >> > Regards,
>>>>> >> > Ouch Whisper
>>>>> >> > 010101010101
>>>>> >> >
>>>>> >>
>>>>> >
>>>>> >
>>>>> >
>>>>> > --
>>>>> > Regards,
>>>>> > Ouch Whisper
>>>>> > 010101010101
>>>>> >
>>>>>
>>>>
>>>>
>>>>
>>>> --
>>>> Regards,
>>>> Ouch Whisper
>>>> 010101010101
>>>>
>>>>
>>
>
>
> --
> Regards,
> Ouch Whisper
> 010101010101
>

Mime
View raw message