pureScale on Linux
We are currently building nanoclusters in several locations worldwide, including here in Dublin. Somehow the lab guys have come up with a way to get pureScale to work on about $500 worth of hardware! Respect!
The nanocluster is a pureScale cluster built on 3 intel Atom boxes with 1 acting as storage and running the demo software, the other two having one CF and one member on each. Gigabit ethernet is used between the nodes.
The nanoclusters (obviously) do not consist of a supported configuration and are not for production use.
Nanoclusters are a great way to get pureScale out there for demos and for clients, ISVs and partners to try it out for themselves. The cluster comes pre-packaged with demos and instructional software.
If you want to get your hands on one of these little beauties. Please contact your friendly local sales, avalanche teams or me for more information or a demo.
Unfortunately we can't give the nanoclusters out on loan for extended periods but we will also be releasing instructions and code to allow you to build your own.
Watch this space...
We are currently setting up the tpc-c benchmark on the cluster. Tpc-c is the standard benchmark for OnLine Transaction Processing ( http://www.tpc.org/tpcc/ ). We will be doing some test runs on the pureScale cluster and some tuning to see what kind of throughput we can get out of the cluster for typical OLTP workloads . We will start out with 4 nodes first with the default parameters, then start tuning and tweaking. Please let me know if you want to know more?
Purescale delivers a high availability, scalable database clustering solution on commodity hardware. PureScale is mainly aimed at OLTP workloads and I believe it delivers on the promise that Oracle RAC has been making for several years and not quite delivering on. It delivers these benefits without the need for applications to be made cluster aware.
I think a lot of companies are looking to their IT to be scalable and flexible these days. Imagine you could buy a small number of commodity servers to run your application(s) on. Then simply add more when you need more resources. Swap servers in easily to help out with the processing load of end of financial year number crunching or the holiday rush on your online store. Pay the licenses fees and running costs when you use extra servers and then easily shut them down and not pay when they are not needed.
I guess this kind of flexibility is (arguably) available as follows:
1) Mainframe with virtualization. This is a great solution for those who have the skill set and budget for it. In my experience many companies are not ready for this. It's also difficult to shut down part of a mainframe!
2) Cloud computing. A great solution if you can "cloud enable" your applications and you trust the cloud service provider (a lot). Again many are not ready for this.
PureScale (especially on Linux / system x as it is available now) can give this kind of flexibility in a much more accessible package.
As part of my job here in Dublin with IBM I'm currently building a 6 node pureScale cluster on systems x with SLES 10. Watch this space for more on this...
...oh yes and please comment if you want to see more.
Today is the day when DB2 10.5 FP4, known as Cancun Release has been published officially!
This DB2 Cancun Release includes many different new features and improvements in differents areas like:
The summary of the enhancements can be found here:
There are some exciting improvements and new features included on the pureScale side, which will make even easier to implement pureScale!
Some of these features are really useful to get started with pureScale like having the possibility to run pureScale using just a basic TCP/IP network or using virtual machines under KVM or VMware ESXi. This is great for who wants to explore pureScale technology just using a basic network or a virtualized environment!
But also, for actual pureScale users, two great enhancements like incremental backups and online REORG will be a huge improvement in terms of system and database maintenance and administration.
If you like me are really looking forward to try all these new features, just go and download the just released DB2 Cancun Release 10.5 FP4 at this link:
Feel free to ask any question or comment you may have on all these new and exciting features for pureScale!
Today I saw that the status of one of our testing pureScale instances was red.
Yes, red, it had a red sign, as this instance is on a PureData System for Transactions. The DB2 pureScale instances panel lets you have a quick look at the status of your instances and the databases deployed on them.
Connecting via ssh to the instance, and trying to run db2instance -list shown that this particular instance was not in a good shape:
db2vr1@compute05:/home/db2vr1> db2instance -list The member, CF, or host information could not be obtained. Verify the cluster manager resources are valid by entering db2cluster -cm -verify -resources. Check the db2diag.log for more information.
Following the tip, I ran db2cluster -cm -verify -resources and it shown that the cluster state was inconsistent. At this point, I had a look at the db2diag.log and I could see that there were some errors related to cluster resources.
After seeing that the issue was due to the cluster resources for pureScale, I decided to try to stop and restart the cluster services with the following commands:
1) Restarting pureScale cluster services
db2vr1@compute05:/home/db2vr1/sqllib/bin> ./db2cluster -cfs -stop -all All specified hosts have been stopped successfully.
db2vr1@compute05:/home/db2vr1/sqllib/bin> ./db2cluster -cfs -start -all All specified hosts have been started successfully.
2) Verifying and repairing the instance
At this point, I tried to verify again the status of the cluster with db2instance command:
db2vr1@compute05:/home/db2vr1/sqllib/bin> db2instance -list The member, CF, or host information could not be obtained. Verify the cluster manager resources are valid by entering db2cluster -cm -verify -resources. Check the db2diag.log for more information.
Now, trying again to repair the cluster resources with the db2cluster command:
db2vr1@compute05:/home/db2vr1/sqllib/bin> db2cluster -cm -repair -resources All cluster configurations have been completed successfully. db2cluster exiting ...
db2vr1@compute05:/home/db2vr1> db2instance -list ID TYPE STATE HOME_HOST CURRENT_HOST ALERT PARTITION_NUMBER LOGICAL_PORT NETNAME -- ---- ----- --------- ------------ ----- ---------------- ------------ ------- 0 MEMBER STOPPED compute05 compute05 NO 0 0 compute05-net1 1 MEMBER STOPPED compute06 compute06 NO 0 0 compute06-net1 128 CF STOPPED compute05 compute05 NO - 0 compute05-net1 129 CF STOPPED compute06 compute06 NO - 0 compute06-net1 HOSTNAME STATE INSTANCE_STOPPED ALERT -------- ----- ---------------- ----- compute06 ACTIVE NO NO compute05 ACTIVE NO NO
3) Starting the instance
So now the pureScale cluster was healthy again, so I was able to finally to start the instance successfully:
db2vr1@compute05:/home/db2vr1> db2start 10/01/2013 13:12:02 0 0 SQL1063N DB2START processing was successful. 10/01/2013 13:12:03 1 0 SQL1063N DB2START processing was successful. SQL1063N DB2START processing was successful.
db2vr1@compute05:/home/db2vr1> db2instance -list
ID TYPE STATE HOME_HOST CURRENT_HOST ALERT PARTITION_NUMBER LOGICAL_PORT NETNAME
-- ---- ----- --------- ------------ ----- ---------------- ------------ -------
0 MEMBER STARTED compute05 compute05 NO 0 0 compute05-net1
1 MEMBER STARTED compute06 compute06 NO 0 0 compute06-net1
128 CF PRIMARY compute05 compute05 NO - 0 compute05-net1
129 CF CATCHUP compute06 compute06 NO - 0 compute06-net1
HOSTNAME STATE INSTANCE_STOPPED ALERT
-------- ----- ---------------- -----
compute06 ACTIVE NO NO
compute05 ACTIVE NO NO
We have heard that a “tens of kilometres” limit applies to the distance between the two sides of a Geographically Dispersed pureScale Cluster (GDPC). Buy why?
This is based on a physical limitation i.e. the speed of light in glass (fibre) which is about 5 µs / km. From this we can calculate a round-trip times from member to CF as follows at these distances:
3km = 30 µs
10km = 100 µs
50 km = 500 µs
100 km = 100 µs (or 1 ms)
300km = 3000 µs (or 3 ms)
This will have a significant effect on the performance of the cluster, especially when we start to get into tens of kilometres. The “normal” times for RDMA actions are of the order of 15 µs so to those we need to add this latency for the distance. Compared to a normal pureScale cluster (all in one location) an RDMA action will be slower at a distance as follows.
3km = 3 times slower
10k = 8 times slower
50k = 33 times slower
100k = 66 times slower
300k = 200 times slower
µs = microseconds or 10-6 seconds
ms = milliseconds or 10-3 seconds
CiaranDeB 2700033FRG Tags:  appliance purescale database transactional puredata workload oltp 1,595 Visits
As with all of the pureSystem family the use of patterns to automate repeatable tasks is a feature of pureData systems.
With pureData here are two types of patterns available:
1) Topology Patterns. Topology patterns will install all of the software required to run pureScale and create the pureScale instance on a number of compute nodes. You can deploy a topology pattern of 2, 4, or 6 nodes. The 2 node topology pattern consists of an instance of 2 members with a cluster caching facilities (CFs) co-located on each of two compute nodes. This is the smallest practical HA installation of Db2. The 4 nodes topology pattern consists of 2 members and 2 CFs on separate compute nodes. The 6 node topology pattern is a 4 member cluster with 2 CFs on separate compute nodes. Of course the more nodes you deploy to the higher the performance and resilience.
2) Database Patterns. A database pattern is essentially a method of storing and reusing database configuration settings. Databases patterns are used to create and configure a database within the instance topology. PureData systems will come with an IBM transaction processing database pattern. You can also "roll your own".
I thought you might be interested in a nice little demo tool that is being being developed by Jorge Mira and Christopher La Pat here in the lab.
This lightweight demo tool's purpose is to graphically demonstrate the key elements of pureScale WLB graphically and in real time on any pureScale database and without changing the databse or application running. It is not for production use!
psMon allows for platform independent monitoring of a pureScale cluster to graphically demonstrate the key elements of pureScale WLB graphically and in real time. PsMon provides the user with a view of a number of useful pieces of data regarding the current operating status of a pureScale cluster. The data displayed is broken down into two graphs:
In addition to the graphs, tables below the system resource graphs provide information on what applications are using the highest amounts of system resources.
The entire client application is built in Java and is therefore platform independent. It is a lightweight executable JAR file that can easily be run from almost any computer and can connect to any machine on which the PSMServer application has been deployed.
I am referring to the standard form of database disaster recovery whereby the production system is duplicated at a second "standby" site. The changes made at the production site are made at the standby site keeping it more or less up to date with the production site. This hardware and software, often costing as much as the production system, only gets used in the case of a pretty major disaster when it takes over the function of the production site. Fortunately these events are quite rare. In my experience the rarity of the disaster scenario makes it psychologically difficult to spend all of that money on stuff that will "probably never get used". This can be an even more onerous decision when the database is clustered and several servers are involved. So what can we do?
Those clever folks at the IBM labs have done it again. Why not simply stretch the cluster out so that half is at one data center and half is at another. If one data center fails for whatever reason the application keeps going. The best ideas are usually simple! Of course we retain the existing features of purescale: High availability, capacity on demand etc. This is the Geographically Dispersed PureScale Cluster (GDPS). More details are available. in this white paper
As Winston Churchill said (and famously paraphrased by a certain Roy Keane years later) "He who fails to plan plans to fail". This applies to any task that is more than trivial. Whether it is creating a new lawn or installing pureScale...
If you are going to be installing pureScale then the installation itself is really easy. Where the preparation comes in is in getting the environment set up beforehand. I strongly recommend that you take a careful look here at the DB2 infocenter "Planning for a IBM DB2 pureScale Feature for Enterprise Server Edition deployment" . This should be your first step towards installing pureScale and done before any of the logistics can fall into place. There are various considerations and checklists here such as:
If you need any help or advice then please drop me a line.