[gpfsug-discuss] data interface and management infercace.
Salvatore Di Nardo
sdinardo at ebi.ac.uk
Wed Jul 15 10:19:58 BST 2015
Thanks for the input.. this is actually very interesting!
Reading here:
https://www.ibm.com/developerworks/community/wikis/home?lang=en#!/wiki/General+Parallel+File+System+%28GPFS%29/page/GPFS+Network+Communication+Overview
,
specifically the " Using more than one network" part it seems to me that
this way we should be able to split the lease/token/ping from the data.
Supposing that I implement a GSS cluster with only NDS and a second
cluster with only clients:
As far i understood if on the NDS cluster add first the subnet
10.20.0.0/16 and then 10.30.0.0 is should use the internal network for
all the node-to-node comunication, leaving the 10.30.0.0/30 only for
data traffic witht he remote cluster ( the clients). Similarly, in the
client cluster, adding first 10.10.0.0/16 and then 10.30.0.0, will
guarantee than the node-to-node comunication pass trough a different
interface there the data is passing. Since the client are just "clients"
the traffic trough 10.10.0.0/16 should be minimal (only token ,lease,
ping and so on ) and not affected by the rest. Should be possible at
this point move aldo the "admin network" on the internal interface, so
we effectively splitted all the "non data" traffic on a dedicated interface.
I'm wondering if I'm missing something, and in case i didn't, what could
be the real traffic in the internal (black) networks ( 1g link its fine
or i still need 10g for that). Another thing I I'm wondering its the
load of the "non data" traffic between the clusters.. i suppose some
"daemon traffic" goes trough the blue interface for the inter-cluster
communication.
Any thoughts ?
Salvatore
On 13/07/15 18:19, Muhammad Habib wrote:
> Did you look at "subnets" parameter used with "mmchconfig" command. I
> think you can use order list of subnets for daemon communication and
> then actual daemon interface can be used for data transfer. When the
> GPFS will start it will use actual daemon interface for communication
> , however , once its started , it will use the IPs from the subnet
> list whichever coming first in the list. To further validate , you
> can put network sniffer before you do actual implementation or
> alternatively you can open a PMR with IBM.
>
> If your cluster having expel situation , you may fine tune your
> cluster e.g. increase ping timeout period , having multiple NSD
> servers and distributing filesystems across these NSD servers. Also
> critical servers can have HBA cards installed for direct I/O through
> fiber.
>
> Thanks
>
> On Mon, Jul 13, 2015 at 11:22 AM, Jason Hick <jhick at lbl.gov
> <mailto:jhick at lbl.gov>> wrote:
>
> Hi,
>
> Yes having separate data and management networks has been critical
> for us for keeping health monitoring/communication unimpeded by
> data movement.
>
> Not as important, but you can also tune the networks differently
> (packet sizes, buffer sizes, SAK, etc) which can help.
>
> Jason
>
> On Jul 13, 2015, at 7:25 AM, Vic Cornell <viccornell at gmail.com
> <mailto:viccornell at gmail.com>> wrote:
>
>> Hi Salvatore,
>>
>> I agree that that is what the manual - and some of the wiki
>> entries say.
>>
>> However , when we have had problems (typically congestion) with
>> ethernet networks in the past (20GbE or 40GbE) we have resolved
>> them by setting up a separate “Admin” network.
>>
>> The before and after cluster health we have seen measured in
>> number of expels and waiters has been very marked.
>>
>> Maybe someone “in the know” could comment on this split.
>>
>> Regards,
>>
>> Vic
>>
>>
>>> On 13 Jul 2015, at 14:29, Salvatore Di Nardo <sdinardo at ebi.ac.uk
>>> <mailto:sdinardo at ebi.ac.uk>> wrote:
>>>
>>> Hello Vic.
>>> We are currently draining our gpfs to do all the recabling to
>>> add a management network, but looking what the admin interface
>>> does ( man mmchnode ) it says something different:
>>>
>>> --admin-interface={hostname | ip_address}
>>> Specifies the name of the node to be used by GPFS
>>> administration commands when communicating between
>>> nodes. The admin node name must be specified as an IP
>>> address or a hostname that is resolved by the host
>>> command to the desired IP address. If the keyword
>>> DEFAULT is specified, the admin interface for the
>>> node is set to be equal to the daemon interface for the
>>> node.
>>>
>>>
>>> So, seems used only for commands propagation, hence have
>>> nothing to do with the node-to-node traffic. Infact the other
>>> interface description is:
>>>
>>> --daemon-interface={hostname | ip_address}
>>> Specifies the host name or IP address _*to be used by
>>> the GPFS daemons for node-to-node communication*_. The
>>> host name or IP address must refer to the commu-
>>> nication adapter over which the GPFS daemons
>>> communicate. Alias interfaces are not allowed. Use the
>>> original address or a name that is resolved by the
>>> host command to that original address.
>>>
>>>
>>> The "expired lease" issue and file locking mechanism a( most of
>>> our expells happens when 2 clients try to write in the same
>>> file) are exactly node-to node-comunication, so im wondering
>>> what's the point to separate the "admin network". I want to be
>>> sure to plan the right changes before we do a so massive task.
>>> We are talking about adding a new interface on 700 clients, so
>>> the recabling work its not small.
>>>
>>>
>>> Regards,
>>> Salvatore
>>>
>>>
>>>
>>> On 13/07/15 14:00, Vic Cornell wrote:
>>>> Hi Salavatore,
>>>>
>>>> Does your GSS have the facility for a 1GbE “management”
>>>> network? If so I think that changing the “admin” node names of
>>>> the cluster members to a set of IPs on the management network
>>>> would give you the split that you need.
>>>>
>>>> What about the clients? Can they also connect to a separate
>>>> admin network?
>>>>
>>>> Remember that if you are using multi-cluster all of the nodes
>>>> in both networks must share the same admin network.
>>>>
>>>> Kind Regards,
>>>>
>>>> Vic
>>>>
>>>>
>>>>> On 13 Jul 2015, at 13:31, Salvatore Di Nardo
>>>>> <sdinardo at ebi.ac.uk <mailto:sdinardo at ebi.ac.uk>> wrote:
>>>>>
>>>>> Anyone?
>>>>>
>>>>> On 10/07/15 11:07, Salvatore Di Nardo wrote:
>>>>>> Hello guys.
>>>>>> Quite a while ago i mentioned that we have a big expel issue
>>>>>> on our gss ( first gen) and white a lot people suggested that
>>>>>> the root cause could be that we use the same interface for
>>>>>> all the traffic, and that we should split the data network
>>>>>> from the admin network. Finally we could plan a downtime and
>>>>>> we are migrating the data out so, i can soon safelly play
>>>>>> with the change, but looking what exactly i should to do i'm
>>>>>> a bit puzzled. Our mmlscluster looks like this:
>>>>>>
>>>>>> GPFS cluster information
>>>>>> ========================
>>>>>> GPFS cluster name: GSS.ebi.ac.uk
>>>>>> <http://gss.ebi.ac.uk/>
>>>>>> GPFS cluster id: 17987981184946329605
>>>>>> GPFS UID domain: GSS.ebi.ac.uk
>>>>>> <http://gss.ebi.ac.uk/>
>>>>>> Remote shell command: /usr/bin/ssh
>>>>>> Remote file copy command: /usr/bin/scp
>>>>>>
>>>>>> GPFS cluster configuration servers:
>>>>>> -----------------------------------
>>>>>> Primary server: gss01a.ebi.ac.uk
>>>>>> <http://gss01a.ebi.ac.uk/>
>>>>>> Secondary server: gss02b.ebi.ac.uk
>>>>>> <http://gss02b.ebi.ac.uk/>
>>>>>>
>>>>>> Node Daemon node name IP address Admin node
>>>>>> name Designation
>>>>>> -----------------------------------------------------------------------
>>>>>> 1 gss01a.ebi.ac.uk <http://gss01a.ebi.ac.uk/>
>>>>>> 10.7.28.2 gss01a.ebi.ac.uk
>>>>>> <http://gss01a.ebi.ac.uk/> quorum-manager
>>>>>> 2 gss01b.ebi.ac.uk <http://gss01b.ebi.ac.uk/>
>>>>>> 10.7.28.3 gss01b.ebi.ac.uk
>>>>>> <http://gss01b.ebi.ac.uk/> quorum-manager
>>>>>> 3 gss02a.ebi.ac.uk <http://gss02a.ebi.ac.uk/>
>>>>>> 10.7.28.67 gss02a.ebi.ac.uk
>>>>>> <http://gss02a.ebi.ac.uk/> quorum-manager
>>>>>> 4 gss02b.ebi.ac.uk <http://gss02b.ebi.ac.uk/>
>>>>>> 10.7.28.66 gss02b.ebi.ac.uk
>>>>>> <http://gss02b.ebi.ac.uk/> quorum-manager
>>>>>> 5 gss03a.ebi.ac.uk <http://gss03a.ebi.ac.uk/>
>>>>>> 10.7.28.34 gss03a.ebi.ac.uk
>>>>>> <http://gss03a.ebi.ac.uk/> quorum-manager
>>>>>> 6 gss03b.ebi.ac.uk <http://gss03b.ebi.ac.uk/>
>>>>>> 10.7.28.35 gss03b.ebi.ac.uk
>>>>>> <http://gss03b.ebi.ac.uk/> quorum-manager
>>>>>>
>>>>>>
>>>>>> It was my understanding that the "admin node" should use a
>>>>>> different interface ( a 1g link copper should be fine), while
>>>>>> the daemon node is where the data was passing , so should
>>>>>> point to the bonded 10g interfaces. but when i read the
>>>>>> mmchnode man page i start to be quite confused. It says:
>>>>>>
>>>>>> --daemon-interface={hostname | ip_address}
>>>>>> Specifies the host name or IP address _*to be used by the
>>>>>> GPFS daemons for node-to-node communication*_. The host name
>>>>>> or IP address must refer to the communication adapter over
>>>>>> which the GPFS daemons communicate.
>>>>>> Alias interfaces are not allowed. Use the original address or
>>>>>> a name that is resolved by the host command to that original
>>>>>> address.
>>>>>>
>>>>>> --admin-interface={hostname | ip_address}
>>>>>> Specifies the name of the node to be used by GPFS
>>>>>> administration commands when communicating between nodes. The
>>>>>> admin node name must be specified as an IP address or a
>>>>>> hostname that is resolved by the host command
>>>>>> tothe desired IP address. If the
>>>>>> keyword DEFAULT is specified, the admin interface for the
>>>>>> node is set to be equal to the daemon interface for the node.
>>>>>>
>>>>>> What exactly means "node-to node-communications" ?
>>>>>> Means DATA or also the "lease renew", and the token
>>>>>> communication between the clients to get/steal the locks to
>>>>>> be able to manage concurrent write to thr same file?
>>>>>> Since we are getting expells ( especially when several
>>>>>> clients contends the same file ) i assumed i have to split
>>>>>> this type of packages from the data stream, but reading the
>>>>>> documentation it looks to me that those internal comunication
>>>>>> between nodes use the daemon-interface wich i suppose are
>>>>>> used also for the data. so HOW exactly i can split them?
>>>>>>
>>>>>>
>>>>>> Thanks in advance,
>>>>>> Salvatore
>>>>>>
>>>>>>
>>>>>>
>>>>>> _______________________________________________
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>>>>>> http://gpfsug.org/mailman/listinfo/gpfsug-discuss
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