Basis – Page 20 – Saptechnicalguru.com

SAP support backbone update

The SAP support backbone update is live per 1.1.2020. Blocking started as of 8.1.2020. If you did not prepare your systems for it, you might loose support functions.

Per 31.07.2020 the sending of EWA’s via RFC towards SAP will no longer work. See OSS note 2923799 – Final Shutdown of RFC Connections From Customer Systems to SAP. At the same date OSS notes downloads via RFC will be fully blocked. Also the RTCCTOOL will stop to work (see oss note 2934203 – ST-A/PI 01T* SP01 – 01U SP00: SAP backbone connectivity for RTCCTOOL on basis 700-731 after RFC shutdown).

You can get or will already get messages like:

SAP note 2847665 – OSS RFC Connection fails will refer you to the SAP Backbone connection update site.

Also on the main SAP support site there is this warning message:

Which refers to first-aid kit OSS note: 2874259 – First Aid Kit for Problems Related to SAP’s Support Backbone Switch-Over Starting on 8 January 2020 .

Questions that will be answered in this blog are:

Where can I find more background information on the SAP support backbone update?
Why can I find first aid support?
Do I need to upgrade SAP solution manager?
How to switch to digitally signed OSS notes?
Do I need to change my OSS RFC’s?
What else do I need to do?
How to check the correct setup in the SAP EWA report?
Where can I find a checklist to see if I am completely done?

Background information on SAP support backbone update

The landing page for SAP support backbone update can be found by following this link.

The webinar recording explaining all the highlights can be found by following this link.

The official OSS note is 2737826 – SAP Support Backbone Update / upcoming changes in SAP Service and Support Backbone interfaces (latest) in January 2020.

2 important OSS notes for quick start of actions:

And the new first aid kit OSS note:

2874259 – First Aid Kit for Problems Related to SAP’s Support Backbone Switch-Over Starting on 8 January 2020

Quick overview of all your systems in SAP service marketplace

SAP now provides the overview of your systems which are not ok in a special online overview. Follow this link. Your result can look like this:

What will change per 1.1.2020?

Basically the connection from SAP solution manager and the on premise SAP systems connection to the SAP backbone will change. This will impact many areas like OSS notes, EWA’s, landscape planning etc.

What do you need to do if you don’t want to loose any functionality?

Solution manager

If you don’t want to loose any functionality in SAP solution manager you will need to upgrade to Solution manager 7.2 to support package 7 or 8. If you are on 8 you have to do less manual work than on 7. On solution manager support packs 5 and 6 some functions will work, but with manual work and limitations. On solution manager 7.1 and solution manager 7.2 up to support pack 3, the connection to SAP support backbone will be lost on 1.1.2020. You can already upgrade to SP8 now and prepare solution manager.

For the automatic configuration of the connectivity follow the instructions in OSS note 2738426 – Automated Configuration of new Support Backbone Communication.

OSS notes

For OSS notes there are 2 changes: the RFC to SAP and digitally signed OSS notes.

For the RFC connection read and follow the instructions from OSS note 2740667 – RFC connection SAPOSS to SAP Service & Support backbone will change (latest) in January 2020.

OSS notes via SNOTE must be switched to digitally signed OSS notes. How to do this: see blog.

Next to this, you will need to change the OSS note RFC destination. The generic user will no longer work. You will need to change it to named technical user, or change to the connection from RFC to https connectivity.

If you setup digitally signed OSS notes there is an option for fallback to insecure.

Attention: this fallback will no longer work after 1.1.2020.

ANST

ANST is a great function to help you find OSS notes relevant for your issue. For more explanation on ANST look at this blog. The ANST reaches out to the SAP support backbone to check for recent notes. To keep the function working you need to setup a new webservice in SOAMANAGER (if the SOAP runtime is not active follow instructions in this blog). To setup the specific webservice follow the instructions in oss note 2730525 – Consuming the Note Search Webservice. Then apply OSS note 2732094 – ANST- Implementing SOAP Based ANST Note Search and 2818143 – SEARCH_NOTES- Implementing SOAP Based Note Search.

While switching to new SAP support backbone you might get a connection error. Follow the instructions from OSS note 2781045 – ANST / ST22 note search “Connection cannot be established” to solve it.

Other calls

See OSS note 2722027 – Certain OSS RFC APIs calls replaced with corresponding web service calls.

Online checklists

SAP has now published online checklists, based on your solution manager version. You can find the checklists on this link.

Support backbone configuration check in EWA report

If you install ST-A/PI 01T sp02 or higher in your system (see OSS note 2827332 – Service Data not Complete due to ST-A/PI not Up-to-date), the EWA report of that system will give information about the correct connection to SAP support backbone and correct use of technical user for the communication.

Example:

In the process OSS note 2802999 - SDCCN activation fails without errors or red icons in Migrate tab might need to be applied as well to solve an SDCCN error.

All background information can be found in OSS note 2823658 – EWA Checks for SAP Backbone Connectivity.

SDCCN error notes

SAP is having some issues with the SDCCN coding for the backbone connectivity. If you experience issues there, check out the following OSS notes:

DMIS plugin notes analyzer

When you are using DMIS plugin for SLT data replication you will need to regularly apply OSS notes to solve bugs. This blog will explain how to quickly analyze the needed notes using the DMC note analyzer program.

Questions that will be answered in this blog are:

How to install the DMC note analyzer programs?
How to run the DMC note analyzer programs?

Installation of the DMC note analyzer programs

The new DMC note analyzer programs are delivered via OSS note 3016862 – Note Analyzers with separated scenarios for ABAP-based Migration and Replication Technology (DMIS2011/DMIS2018/DMIS2020/SAP S/4HANA). Minor manual work is required.

These new programs are replacing the old DMC_NOTE_ANALYZER program.

The new programs are separated by function:

Scenario	Report name
Object Based Transformation (OBT)	CNV_NOTE_ANALYZER_OBT
ABAP Integration for SAP Data Intelligence (DI)	CNV_NOTE_ANALYZER_DI
S4HANA Migration Cockpit (MC)	CNV_NOTE_ANALYZER_MC_EXT
SAP Landscape Transformation (SLT) Replication Server	CNV_NOTE_ANALYZER_SLT
Near Zero Downtime Technology (NZDT)	CNV_NOTE_ANALYZER_NZDT

Running the new program for use case SLT

With transaction SE38 start program CNV_NOTE_ANALYZER_SLT:

Now start the run.

After the run is done the missing notes are listed:

Installation of the old DMC note analyzer program

The DMC note analyzer program is delivered via SAP oss note 2596411 – SLT / NZDT / S4HANA Migration Cockpit (DMIS2011 SP11-SP15; DMIS2018; S/4HANA 1610, 1709 & 1809) – Note Analyzer.

Minor manual work is needed for the implementation of this OSS note.

Running the old DMC note analyzer

With transaction SE38 start program DMC_NOTE_ANALYZER. On the start screen select whether you want to check for the central system or the source system:

Now start the run.

After the run is done the missing notes are listed:

From the overview you can start to download the notes and apply them.

SGEN: code generation

After any support pack and upgrade you want to check and make sure the ABAP code in the system is ok and pre-compiled for business use. The SGEN code generator tool does the job for you.

Questions that will be answered in this blog are:

How to run SGEN?
How can I see the result behind SGEN?

Running SGEN

Starting SGEN is simple by starting the transaction code SGEN. The initial screen looks like this:

Select the option you want to use. The most common feature option is the Regenerate after SAP system upgrade. Press continue. You now reach the load generator screen to distribute the load across many parallel processes:

Select the servers and press continue.

SGEN is a resource intensive process: performance during the run will be pretty low....

In the load monitor you now release the job and you can start to monitor it:

You can also monitor in SM37 the batch job for program RSPARAGENER8M .

Data behind SGEN

Table GENSETM contains the results of the generation run. The field GENSTATUS is the generation status. Values of this field:

X = generated

E or S = error

I = initial

Touch single program or table

SGEN is a mass transaction for large amounts and can run quite long. If you only need to regenerate single program or table, read this blog.

Background

More background information on SGEN can be found in the FAQ note: 1989778 – FAQ: SGEN.

Other notes:

Data archiving improvement notes 2018

In 2018 SAP ran an improvement project which resulted into a set of OSS notes that will make data archiving more robust and easy.

All of these notes come with manual work. Select the ones really useful.

Archiving write process improvements

Write variant maintenance has been made easier by allowing copying of variants (useful if you have many plants and company codes and want to store each one in different archive file): 2520093 – Archive administration: Enhanced variant maintenance (writing, preprocessing, and postprocessing).

To be able to detail the written file name of the archive file implement this oss note: 2637105 – Print list for archiving write jobs: Placeholders for session numbers, archive file key in title.

Archiving storage process improvements

Archiving system technical check button is available in OAC0, but not in SARA. After applying this note you can also check it in the technical settings in SARA: 2599263 – Connection test for storage systems for archiving object.

Deletion process improvements

To be able to quickly continue with interrupted archiving sessions apply this note 2520094 – Continue: Information on existence of interrupted or incomplete archiving sessions.

This note will implement checks to warn you about uncompleted previous store and delete runs: 2586921 – Run selection for deletion: Information about the existence of unstored archive files.

Some archiving object use the AIS (archiving information system) to enable the end user a quick retrieval of archiving information. This note will give warning before start of deletion if the AIS is note active for the object: 2624077 – Starting delete jobs: Check for active info structures.

Archiving overview and logging improvement

To get a better overall overview of all logs apply OSS note 2433546 – Archive administration logs: Information about errors in hierarchy display. Showing only success message is possible after applying OSS note 2855641 – Logs: New option “Success Messages Only” for detail log.

Direct navigation to Archive File Browser: apply OSS note 2544517 – Archive administration: Direct navigation to ArchiveFileBrowser. This note only gives you a link. You can already start the archive file browser using transaction AS_AFB:

Note 2823924 – Archive File Browser: Messages that do not belong to the Archive File Browser are output solves a bug in the Archive File Browser.

TAANA improvement to count dynamic subfields

SAP has done an improvement on TAANA to count dynamic subfields. This blog will explain how. More generic information on TAANA can be found in this blog.

Questions that will be answered in this blog are:

How to get the new TAANA function for dynamic subfields?
How to run TAANA dynamic subfields?

How to get the new TAANA function for dynamic subfields?

Simply apply improvement OSS note 2614476 – TAANA: Several dynamic subfields with reference to same reference field.

How to run dynamic subfields in TAANA?

We will use table JEST as example. This table as a pretty annoying setup. The main field OBJNR is in fact 2 fields: the first 2 characters are object identification, and the second part is a number for the object. But if you want to analyze how many objects type you have this is problematic with SE16.

In TAANA we can use the dynamic subfields. Start transaction TAANA and create an Ad Hoc Anlysis for table JEST. First hit Execute to start, enter table JEST and in this screen hit the Ad Hoc Variant button:

Now select the OBJNR field:

In the Offset field fill 0. And in Subfield length 2. This means take first 2 characters of field OBJNR. Press ok and start the run in the background.

The end result is a cross section with counts on the types of the first 2 characters in JEST-OBJNR:

SE16S and SE16H

For some searches, also have a look at SE16S and SE16H.

SE16H: HANA specific implementation of SE16

SE16H is a HANA specific implementation of SE16. This blog will explain the additional functions of SE16H.

Questions that will be answered in this blog are:

How to use SE16H?
Where to find full list of SE16H functions?
Which bug fix notes for SE16H should I apply?

SE16H: HANA specific implementation of SE16

SE16 or SE16N are one of the most used transactions for data analysis on any SAP system. SE16H is the HANA specific implementation which leverages some of the HANA specific strengths.

Transaction code to start is simply SE16H. We now enter VBAK as example table. Just pressing execute will give simple list of first 500 entries. Nothing new.

Now we run again, but tick the Group and Sort tick boxes for the Document Category field:

The output now is a sum of the sales orders in table VBAK grouped by identical Document Category:

TAANA vs SE16H vs SE16S

If you run on HANA, the SE16H transaction is a faster option than the classical TAANA transaction, since SE16H runs online and TAANA runs as batch.

SE16H is for lookup of single table. SE16S can search for content in one or multiple tables. More on SE16S in this blog.

For usage of SE16N, read this blog.

List of all SE16H functions

The full list of all SE16H functions can be found in OSS note 1636416 – CO-OM tools: Functions of transaction SE16H.

Interesting ones are: aggregation, drill down, sorting, totaling, outer joins.

New function is the use of a formula editor. This can be used after applying OSS note 2795867 – CO-OM tools: Implementation of formula editor in SE16H.

SE16H bug fix notes

Please consider the following bug fix OSS notes for SE16H:

SAP database growth control: data archiving business discussions

This blog addresses the main challenge in SAP data archiving for functional object: the discussions with the business.

This blog will give answers to the following questions:

When to start data archiving discussion with the business?
How to come to good retention periods?
What are arguments for not archiving certain data?

Data archiving discussion with the business

Unlike technical data deletion, functional data archiving cannot be done without proper business discussion and approval.

Depending on your business several aspects for data are important:

Auditing and Sox needs
Tax and legal retention periods
Product data requirement
And so on…..

Here are some rules of thumb you can use before considering to start up the business discussions about archiving:

Rule of thumb 1: the system is pretty new. At least wait 3 years to get an insight into which tables are growing fast and are worth to investigate for data archiving.

Rule of thumb 2: if your system is growing slowly, but the infrastructure capabilities grow faster: only perform technical clean up and don't even start functional data archiving.

Rule of thumb 3: if you are on HANA: check if the data aging concept for functional objects is stable enough and without bugs. Data aging does not require much work, it is only technical and it does not require much business discussions. Data retrieval from end user perspective is transparent.

Data analysis before starting the discussion

If your system is growing fast and/or you are getting performance complaints, then you need to do proper data analysis before starting any business discussion.

Start with proper analysis on the data. Use the TAANA tool to get insights into the data: how is the distribution of data per document type, per year, per plant/company code etc. If you want to propose retention period of let’s say 5 years, you can use the TAANA results to show what percentage of data you can move out of the database.

Secondly: if you have an idea on which data you want to archive, first execute a trial run on a recent production copy. There might be functional blocks that prevent you from archiving data (like not closed documents).

Third important factor is the ease of data retrieval. Some object have a nice simple data retrieval function, and some are really terrible. If the retrieval is good, the business will more easily accept a shorter retention period. Read more on technical data retrieval in this blog.

As last step you can start the business case: how much data will be saved (and how much money hence will be save) and how much performance would be gain. And how much time is needed to be invested for setting up, checking (testing!) and running the data archiving runs.

In practice data archiving business case is only present in very large systems of 5 TB and larger. This sizing tipping point changes in time as hardware gets cheaper and hourly manpower costs go up.

The discussion itself

Take must time in planning for the discussion itself. It is not uncommon that archiving discussions take over a year to complete. The better you are prepared the easier the discussion. It also helps to have a few real performance pain points to get solved via data archiving. There is normally a business owner for this pain point who can help push data archiving.

SAP database growth control: data archiving run

This blog will explain how to execute a data archiving run.

Questions that will be answered in this blog are:

Which settings do I need to make or check before data archiving run?
How to perform the data archiving run?
How to validate the data archiving run?
How to retrieve that archived data?

This blog assumes you have finished the basic technical data archiving setup as described in this blog. It also assumes you have made agreements with your business on the retention periods. For more information and tips on discussions with the business teams on data archiving, read this blog.

If you are looking for specific functional data archiving runs:

Functional data archiving example: purchase requisitions

To explain the functional data archiving we will use Purchase Requisitions as example. Technical object name is MM_EBAN.

To see which tables are archived hit the Database Tables button. Here you can see the list of tables from which data potentially be archived:

If you want to see the other way around, which table is used in archiving objects, do put in the table as entry point, to retrieve list of archiving objects. In this example archiving objects that delete from table EBAN:

Dependency of objects

By clicking the top left button on the archiving object you get the archiving dependency view. For MM_EBAN this is pretty simple: it has no dependencies.

As example for dependencies this is the overview for sales orders (SD_VBAK):

Here you can see that before you can archive sales orders, you should archive the billing documents first. And for the billing documents, you should archive the deliveries first.

Functional archiving settings

First we have to make or check the object specific functional archiving settings.

In the case of purchase requisitions we have to set the retention periods per document type:

Pre-processing step

Some archive object have a pre-processing step. MM_EBAN has one as well. In this step data is selected and marked for archiving (many times by setting deletion flag or other indicator).

In the step create the variant (give it a useful name) by putting in the name and pressing Edit. On the next screen fill out your data select the log level. Go back to the first screen and select the start data and spool parameters. When both lights are green, hit the execute button. When you click the job log button you check for the results.

Example of result of pre-processing run:

As you can see not all selected data is archived. Transactions that are not completed from business point of view will not be flagged for archiving.

Write run

If you have done the pre-processing step, continue with the write step. Principle is the same: select the data and log level. Important in the write step is to correctly fill the Archiving Session Note with a useful text. This text is put as label on the archive file for later retrieval:

When done plan the job and execute. Result looks like:

Pending on your technical system settings the file will be stored automatically or you still need to do this manually.

Storage run

If you have setup the system to store files in content server, you first have to execute storage run. For more details see this dedicated blog.

Deletion run

Finally we can now start the deletion run: the actual clean up of old data happens now.

Select the data files you want to archive and start the run.

Word of care with deletion: please don't select too much files and subsection in one go. Each file sub section will result into a deletion job. The deletion will put significant load on the database, since it will be pushing out a lot of data. If you are not careful you will launch easily 20 or more heavy deletion jobs that run in parallel and that might severely decrease system performance.

Result of archiving deletion run:

Checking archive result

The result checking is possible by looking at the technical correctness of the archive file.

In the archiving object choose the Overview button. Then select the archive file you want to inspect. A correct file should like like this:

In the testing phases and first production runs, you also want to do record counting. A good way is to run the TAANA transaction for key tables you want to archive before the archiving and after the archiving. The difference should match the deletion counter on the write and deletion logs. If you find differences: check for bug fix OSS notes.

Data retrieval

Retrieving archived data is different per archived object. Some retrieval is nicely integrated into the normal transaction. Some require extra transaction to run. Some retrieval is via special program.

Data retrieval of purchase requisitions can be done via SARA and choosing the read option.

Here you first need to manually select the archive files to read from (see I did not give the note and regret it, since the file has no meaning now…):

Result after reading looks like this:

More on data retrieval in this dedicated blog.

OSS notes check

Before starting to check the data archiving for an object, it is best to check and read the OSS notes for the pre-processing, write, delete and read programs. Apply the bug fix notes and read about certain aspects, before you have time-consuming effort to figure out you have a bug or a certain feature that is documented inside the notes.

Controlling amount of parallel batch jobs

The deletion phase of archiving can lead to uncontrolled amount of parallel batch jobs. See this dedicated blog on how you can control it.

Data archiving run statistics

Transaction SAR_DA_STAT_ANALYSIS can be used to collect statistics on the data archiving runs:

FIORI app

If you are running recent version of S4HANA, you can also use a FIORI app for monitoring the data archiving runs. Read more in this dedicated blog.

Further optimizations

Further optimizations:

SAP database growth control: data archiving general setup

This blog will explain the general technical setup to be performed for SAP data archiving.

Questions that will be answered in this blog are:

Which generic settings do I need to make for data archiving in the technology domain?
Why should I use a content server to store archive files?

For getting insights in what to archive, read this dedicated blog first.

Data archiving content server setup

For data archiving you can use the file system for storing the archive files. This you can do to perform initial testing. For productive use it is best to store the archive files in a content server. It will not be the first time an overzealous basis person in need for file storage deletes some old files in a directory called /archive…..

After you install the content server, set up in OAC0 the customizing for the content server to use it for Archivelink:

More details are explained in OSS note 2452889 – Assign a content repository to an Archiving Object.

For more details on content server read this dedicated blog.

For file naming convention read OSS note: 1791466 – How to avoid running out of available file names when archiving.

Data archiving general technical settings

Now start transaction SARA:

In this initial screen no object is selected. Now press the Customizing button.

Set the Cross-Client File Names/Paths to your needs. You can do that from this menu, or directly from the FILE transaction.

Set the physical path name to be used:

Even when you use content server the file will first be written to physical path for temporary storage.

And check the archive file name:

Technical settings per archiving object

Per archiving object you can set the technical settings. Normally you keep settings the same per object. Only for very large installations with archiving or special needs, you might want to deviate.

In the technical settings per data archiving object set the following:

Important settings to set:

Max size in MB or the max objects
Check the variants (some variants for production have still deliberately the test tick box as on: you have to change it)
Best to leave the delete jobs to Not scheduled (large archiving runs can create many files and many deletion jobs to kick in at the same time): best to do this manually in controlled way
Start storage automatically or manually is a choice for you
Best to store before deletion. This is the most conservative setting.
Best to delete only from storage system: if file is not stored properly in any way, deletion will not have. This is the most conservative setting.

Actual data archiving runs

How to execute the actual data archiving runs is explained in this dedicated blog.

For specific objects:

Data retrieval

Data retrieval from archive is explained in this dedicated blog.

2018 improvement notes on Data Archiving

In 2018 SAP released several improvement OSS notes on data archiving. Description can be found in this blog.

Controlling amount of parallel batch jobs

The deletion phase of archiving can lead to uncontrolled amount of parallel batch jobs. See this dedicated blog on how you can control it.

FIORI tile for monitoring data archiving runs

There is a FIORI tile for monitoring data archiving runs: read this blog.

FIORI last digit patching

Questions that will be answered in this blog are:

What are the current UI5 versions available and supported?
How to perform UI5 last digit patching?
When to patch and when to upgrade to new FIORI server?

Current UI5 versions available

The current UI5 version overview is published by SAP on this site.

The overview gives information on the main versions (like 1.56, 1.58, etc) and the available last digit patches (like 1.56.14, 1.58.5, etc).

Your own version can be found with this URL:

http(s)://<your server><your port>/sap/public/bc/ui5_ui5/index.html

Example:

This server has versions 1.48 (last digit patch 13) and 1.52 (last digit patch 8).

Last digit patching

To patch the last digit to the newest version, you first look for the corresponding OSS note. Search for term “ABAP SAPUI5 1.xx release” with xx being your release. For our example it is oss note 2550980 – ABAP SAPUI5 1.52 release. Or take the generic note: 3155948 – ABAP SAPUI5 patch version update.

The note describes per last digit version which file to download and which FLP note to apply after you do the patching.

In this example we will patch to level 1.52.23. The note tells us do use this file and note:

Download this file from the SAP software download section.

Check if the last digit patching program needs bug fix OSS notes ( /UI5/UI5_UPLOAD_PATCH_TO_MIME ).

2614248 - Upload UI5 patch error: Unable to lock the source code to edit
2997207 - /UI5/UI5_UPLOAD_PATCH_TO_MIME: Load UI5 archive from application server
3075898 - /UI5/UI5_UPLOAD_PATCH_TO_MIME: Problems detected with transport-related checks of Change Ctrl Mgmt
3145139 - Fix content type of UI5 files with hashed names in MIME Repository
3153462 - UI Library Patch Error while parsing an XML stream: 'BOM / charset detection failed'.
3220439 - Prerequisite for improvement of UI5 patch installation
3271129 - "File contains no Demokit" error in report /UI5/UI5_UPLOAD_PATCH_TO_MIME for UI5 1.102 release
3280413 - SAPUI5 patch upload: Prevent inconsistent file state after Virus Scan misconfiguration

The upload and processing of the last digit patch file can take a long time (typically 1 hour). If you don’t take measures the system will dump after 10 minutes with a time-out.

Goto RZ11 and set rdisp/max_wprun_time to value 12000 (and undo this after the patching). In newer versions of netweaver the parameter is rdisp/scheduler/max_runtime, which needs to be set to 120m.

Now start program /UI5/UI5_UPLOAD_PATCH_TO_MIME:

The file has to point to the file you have downloaded to your desktop. Use F4 to select the correct file. The request /task must be a valid unreleased workbench request.

First run in test mode. Wait until it is done (1 hour is normal…). If the result is ok, remove the tick box for test mode and run real mode (yes, 1 more hour to wait).

End result should look like:

After the application of the patch, apply the FLP note (in this case note 2605065).

Now you can start the version overview again to see if the patching was ok:

As you can see the 1.52 version is now updated to level 1.52.23. The 1.48 version is the same.

More background in OSS note 2630700 – SAPUI5 patch update fails.

Transport of last digit patch to Q and P systems

When you want to apply last digit patch on Q and P systems, you can move the transport you have selected in the upload step. The unfortunate thing is that the import to Q and P of this transport also takes about 1 hour. This means you need to properly plan the import (especially on production select a time where no users are using FIORI apps).

Patching versus upgrading

The goal of last digit patching is simple: it solves bugs in the SAP delivered UI5 libraries. But it can also bring new bugs.

Best patching strategy: only patch when you have a bug that must be solved. Then patch to latest version. Don't think last minus one, since the UI5 patches come every 2 to 4 weeks: just take latest one. If your system is stable: don't patch.

Upgrading to a higher FIORI frontend server will give you new libraries which will have new functions. Also: the higher frontend servers have better performance due to faster ABAP kernel, better caching features etc. If you are using newer S4HANA solutions, you will be forced to upgrade frontend server to specific minimum version.

Best practice upgrading: if you are using central FIORI gateway server plan for upgrade every year or every 2 years at minimum. Every year at least apply support pack: the support pack will also to do last digit patching as well. After support pack or full version upgrade immediately patch to last digit version available before starting the testing.

Background OSS notes

Background notes: