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DS8000 Enhancements for IBM System z10 EC
On Tuesday, I covered much of the Feb 26 announcements, but left the IBM System Storage DS8000 for today so that it can haveits own special focus.
Many of the enhancements relate to z/OS Global Mirror, which we formerly called eXtended Remote Copy or "XRC", not to be confused with our "regular" Global Mirror that applies to all data. For those not familiar with z/OS Global Mirror, here is how it works. The production mainframe writes updates to the DS8000, and the DS8000 keeps track of these in cache until a "reader" can pull them over to the secondary location.The "reader" is called System Data Mover (SDM) which runs in its own address space under z/OS operating system. Thanks to some work my team did several years ago, z/OS Global Mirror was able to extend beyond z/OS volumes and include Linux on System z data. Linux on System z can use a "Compatible Disk Layout" (CDL) format (now the default) that meetsall the requirements to be included in the copy session.
IBM has over 300 deployments of z/OS Global Mirror, mostly banks, brokerages and insurance companies. The feature can keep tens of thousands of volumes in one big "consistency group" and asynchronously mirror them to any distance on the planet, with the secondary copy recovery point objective (RPO) only a few seconds behind the primary.
Extended Distance FICON
Extended Distance FICON is an enhancement to the industry-standard FICON architecture (FC-SB-3) that can help avoid degradation of performance at extended distances by implementing a new protocol for "persistent" Information Unit (IU) pacing. This deals with the number of packets in flight between servers and storage separated by long distances, andcan keep a link fully utilized at 4Gpbs FICON up to 50 kilometers. This is particularly important for z/OS GlobalMirror "reader" System Data Mover (SDM). By having many "reads" in flight, this enhancementcan help reduce the need for spoofing or channel-extender equipment, or allow you to choose lower-costchannel extenders based on "frame-forwarding" technology. All of this helps reduce your total cost of ownership (TCO)for a complete end-to-end solution.
This feature will be available in March as a no-charge update to the DS8000 microcode.For more details, see the [IBM Press Release]
z/OS Global Mirror process offload to zIIP processors
To understand this one, you need to understand the different "specialty engines" available on the System z.
On distributed systems where you run a single application on a single piece of server hardware, you mightpay "per server", "per processor" or lately "per core" for dual-core and quad-core processors. Software vendors were looking for a way to charge smaller companies less, and larger companies more. However, you might end up paying the same whether you use 1GHz Intelor 4GHz Intel processor, even though the latter can do four times more work per unit time.
The mainframe has a few processors for hundreds or thousands of business applications.In the beginning, all engines on a mainframe were general-purpose "Central Processor" or CP engines. Based on theircycle rate, IBM was able to publish the number of Million Instructions per Second (MIPS) that a machine witha given number of CP engines can do. With the introduction of side co-processors, this was changed to "Millionsof Service Units" or MSU. Software licensing can charge per MSU, and this allows applications running in aslittle as one percent of a processor to get appropriately charged.
One of the first specialty engines was the IFL, the "Integrated Facility for Linux". This was a CP designatedto only run z/VM and Linux on the mainframe. You could "buy" an IFL on your mainframe much cheaper than a CP,and none of your z/OS application software would count it in the MSU calculations because z/OS can't run on theIFL. This made it very practical to run new Linux workloads.
In 2004, IBM introduced "z Application Assist Processor" (zAAP) engines to run Java, and in 2006, the "z Integrated Information Processor" (zIIP) engines to run database and background data movement activities.By not having these counted in the MSU number for business applications, it greatly reduced the cost for mainframe software.
Tuesday's announcement is that the SDM "reader" will now run in a zIIP engine, reducing the costs for applicationsthat run on that machine. Note that the CP, IFL, zAAP and zIIP engines are all identical cores. The z10 EC hasup to 64 of these (16 quad-core) and you can designate any core as any of these engine types.
Faster z/OS Global Mirror Incremental Resync
One way to set up a 3-site disaster recovery protection is to have your production synchronously mirrored to a second site nearby, and at the same time asynchronously mirrored to a remote location. On the System z,you can have site "A" using synchronous IBM System Storage Metro Mirror over to nearby site "B", and alsohave site "A" sending data over to size "C" using z/OS Global Mirror. This is called "Metro z/OS Global Mirror"or "MzGM" for short.
In the past, if the disk in site A failed, you would switch over to site B, and then send all the data all over again. This is because site B was not tracking what the SDM reader had or had not yet processed.With Tuesday's announcement, IBM has developed an "incremental resync" where site B figures out what theincremental delta is to connect to the z/OS Global Mirror at site "C", and this is 95% faster than sendingall the data over.
IBM Basic HyperSwap for z/OS
What if you are sending all of your data from one location to another, and one disk system fails? Do you declare a disaster and switch over entirely? With HyperSwap, you only switch over the disk systems, but leave therest of the servers alone. In the past, this involved hiring IBM Global Technology Services to implementa Geographically Dispersed Parallel Sysplex (GDPS) with software that monitors the situation and updates thez/OS operating system when a HyperSwap had occurred. All application I/O that were writing to the primary locationare automatically re-routed to the disks at the secondary location. HyperSwap can do this for all the disk systems involved,allowing applications at the primary location to continue running uninterrupted.
HyperSwap is a very popular feature, but not everyone has implemented the advanced GDPS capabilities.To address this, IBM now offers "Basic HyperSwap", which is actually going to be shipped as IBMTotalStorage Productivity Center for Replication Basic Edition for System z. This will run in a z/OSaddress space, and use either the DB2 RDBMS you already have, or provide you Apache Derby database for thosefew out there who don't have DB2 on their mainframe already.
Update: There has been some confusion on this last point, so let me explain the keydifferences between the different levels of service:
Basic HyperSwap: single-site high availability for the disk systems only
GDPS/PPRC HyperSwap Manager: single- or multi-site high availability for the disk systems, plus some entry-level disaster recovery capability
GDPS/PPRC: highly automated end-to-end disaster recovery solution for servers, storage and networks
I apologize to all my colleagues who thought I implied that Basic HyperSwap was a full replacement for the morefull-function GDPS service offerings.
Extended Address Volumes (EAV)
Up until now, the largest volume you could have was only 54 GB in size, and many customers still are using 3 GB and 9 GB volume sizes. Now, IBM will introduce 223 GB volumes. You can have any kind of data set on these volumes,but only VSAM data sets can reside on cylinders beyond the first 65,280. That is because many applications still thinkthat 65,280 is the largest cylinder number you can have.
This is important because a mainframe, or a set of mainframes clustered together, can only have about 60,000disk volumes total. The 60,000 is actually the Unit Control Block (UCB) limit, and besides disk volumes, youcan have "virtual" PAVs that serve as an alias to existing volumes to provide concurrent access.
Aside from the first item, the Extended Distance FICON, the other enhancements are "preview announcements" which means that IBM has not yet worked out the final details of price, packaging or delivery date. In many cases, the work is done, has been tested in our labs, or running beta in select client locations, but for completeness I am required to make the following disclaimer:
All statements regarding IBM's plans, directions, and intent are subject to change or withdrawal without notice. Availability, prices, ordering information, and terms and conditions will be provided when the product is announced for general availability.