[Gluster-users] disperse volume brick counts limits in RHES

[Alastair Neil]

so the bottleneck is that computations with 16x20 matrix require  ~4 times
the cycles?  It seems then that there is ample room for improvement, as
there are many linear algebra packages out there that scale better than
O(nxm).  Is the healing time dominated by the EC compute time?  If Serkan
saw a hard 2x scaling then it seems likely.

-Alastair




On 8 May 2017 at 03:02, Xavier Hernandez <xhernandez at datalab.es> wrote:

> On 05/05/17 13:49, Pranith Kumar Karampuri wrote:
>
>>
>>
>> On Fri, May 5, 2017 at 2:38 PM, Serkan Çoban <cobanserkan at gmail.com
>> <mailto:cobanserkan at gmail.com>> wrote:
>>
>>     It is the over all time, 8TB data disk healed 2x faster in 8+2
>>     configuration.
>>
>>
>> Wow, that is counter intuitive for me. I will need to explore about this
>> to find out why that could be. Thanks a lot for this feedback!
>>
>
> Matrix multiplication for encoding/decoding of 8+2 is 4 times faster than
> 16+4 (one matrix of 16x16 is composed by 4 submatrices of 8x8), however
> each matrix operation on a 16+4 configuration takes twice the amount of
> data of a 8+2, so net effect is that 8+2 is twice as fast as 16+4.
>
> An 8+2 also uses bigger blocks on each brick, processing the same amount
> of data in less I/O operations and bigger network packets.
>
> Probably these are the reasons why 16+4 is slower than 8+2.
>
> See my other email for more detailed description.
>
> Xavi
>
>
>>
>>
>>     On Fri, May 5, 2017 at 10:00 AM, Pranith Kumar Karampuri
>>     <pkarampu at redhat.com <mailto:pkarampu at redhat.com>> wrote:
>>     >
>>     >
>>     > On Fri, May 5, 2017 at 11:42 AM, Serkan Çoban
>>     <cobanserkan at gmail.com <mailto:cobanserkan at gmail.com>> wrote:
>>     >>
>>     >> Healing gets slower as you increase m in m+n configuration.
>>     >> We are using 16+4 configuration without any problems other then
>> heal
>>     >> speed.
>>     >> I tested heal speed with 8+2 and 16+4 on 3.9.0 and see that heals
>> on
>>     >> 8+2 is faster by 2x.
>>     >
>>     >
>>     > As you increase number of nodes that are participating in an EC
>>     set number
>>     > of parallel heals increase. Is the heal speed you saw improved per
>>     file or
>>     > the over all time it took to heal the data?
>>     >
>>     >>
>>     >>
>>     >>
>>     >> On Fri, May 5, 2017 at 9:04 AM, Ashish Pandey
>>     <aspandey at redhat.com <mailto:aspandey at redhat.com>> wrote:
>>     >> >
>>     >> > 8+2 and 8+3 configurations are not the limitation but just
>>     suggestions.
>>     >> > You can create 16+3 volume without any issue.
>>     >> >
>>     >> > Ashish
>>     >> >
>>     >> > ________________________________
>>     >> > From: "Alastair Neil" <ajneil.tech at gmail.com
>>     <mailto:ajneil.tech at gmail.com>>
>>     >> > To: "gluster-users" <gluster-users at gluster.org
>>     <mailto:gluster-users at gluster.org>>
>>     >> > Sent: Friday, May 5, 2017 2:23:32 AM
>>     >> > Subject: [Gluster-users] disperse volume brick counts limits in
>>     RHES
>>     >> >
>>     >> >
>>     >> > Hi
>>     >> >
>>     >> > we are deploying a large (24node/45brick) cluster and noted
>>     that the
>>     >> > RHES
>>     >> > guidelines limit the number of data bricks in a disperse set to
>>     8.  Is
>>     >> > there
>>     >> > any reason for this.  I am aware that you want this to be a
>>     power of 2,
>>     >> > but
>>     >> > as we have a large number of nodes we were planning on going
>>     with 16+3.
>>     >> > Dropping to 8+2 or 8+3 will be a real waste for us.
>>     >> >
>>     >> > Thanks,
>>     >> >
>>     >> >
>>     >> > Alastair
>>     >> >
>>     >> >
>>     >> > _______________________________________________
>>     >> > Gluster-users mailing list
>>     >> > Gluster-users at gluster.org <mailto:Gluster-users at gluster.org>
>>     >> > http://lists.gluster.org/mailman/listinfo/gluster-users
>>     <http://lists.gluster.org/mailman/listinfo/gluster-users>
>>     >> >
>>     >> >
>>     >> > _______________________________________________
>>     >> > Gluster-users mailing list
>>     >> > Gluster-users at gluster.org <mailto:Gluster-users at gluster.org>
>>     >> > http://lists.gluster.org/mailman/listinfo/gluster-users
>>     <http://lists.gluster.org/mailman/listinfo/gluster-users>
>>     >> _______________________________________________
>>     >> Gluster-users mailing list
>>     >> Gluster-users at gluster.org <mailto:Gluster-users at gluster.org>
>>     >> http://lists.gluster.org/mailman/listinfo/gluster-users
>>     <http://lists.gluster.org/mailman/listinfo/gluster-users>
>>     >
>>     >
>>     >
>>     >
>>     > --
>>     > Pranith
>>
>>
>>
>>
>> --
>> Pranith
>>
>>
>> _______________________________________________
>> Gluster-users mailing list
>> Gluster-users at gluster.org
>> http://lists.gluster.org/mailman/listinfo/gluster-users
>>
>>
> _______________________________________________
> Gluster-users mailing list
> Gluster-users at gluster.org
> http://lists.gluster.org/mailman/listinfo/gluster-users
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.gluster.org/pipermail/gluster-users/attachments/20170508/dcd83ad2/attachment.html>