How to read the size of the member of a pds file. A pds file has many members. If we browse a pds we can see the member names, their creation date, time user, size, etc.
So how to get these attributes separately in variables.
As Bruce mentioned LMMFIND will have the ISPF statistics for a PDS member. Make sure to use the STATS YES on the service. Also, you may need to check for extended stats (variable ZLEXT ). A site may chose to use extended stats if the member size exceeds 64K. Please refer to the ISPF services Guide. Below is the link for LMMFIND in the 2.1 manual.
https://www.ibm.com/support/knowledgecenter/SSLTBW_2.1.0/com.ibm.zos.v2r1.f54sg00/lmmfind.htm%23lmmfind
If running under TSO/ISPF (you can do this in batch as well), you can use the LMMFIND service with the stats(yes) option. You will have to do
lminit
lmopen
before you do the LMFIND. Also as zarchasmpgmr you will need to do LMCLOSE and LMFREE
If you want to display a member list, have a look at LMMDISP
Be aware that the statistics you write about are maintained by ISPF. There are many ways to create a member outside of ISPF, and those members will not have those statistics. The ISPF service LMMSTATS will set those stats (the 3.5 R panel is a front end to that service). The order of calls is
LMINIT
LMMSTATS
LMFREE
For some reason, LMMSTATS doesn't require the LMOPEN and LMCLOSE services.
It's been ages, but if the PDS does not have ISPF stats (or the STATS are dubious (eg they can be changed outside of ISPF)). Then you could look to processing the directory.
However, by default a PDS directory doesn't contain that much info, so unless ISPF stats exist you couldn't get much info. What a PDS directory does have is a user-definable area and it's that area hat ISPF utilises. This area is preceeded by a length descriptor (see link for more info).
Another reason why ISPF stats may not exists or be accurate, is that, I think (if I recall correctly), that you can remove the stats, which can free some directory space (potentially get around E37 Abend or circumvent it happening).
I can't recall having tried with Rexx (did write an Assembler PDS unload utility), but you might be able to open and read the directory using EXECIO on the BASE name of the PDS (ie not including (member)).
The directory is blocked at 256 bytes. More info in regards to the structure can be found here PDS Directory. I don't believe that this would work properly for PDSE's though.
Related
I am building a large private (ie used behind a firewall) PWA and wondering how to improve the diagnostics if/when my users hit issues. I already have an error manager which uses navigator.sendBeacon to log the error on the server, but that lacks detailed info of what led up to that point.
A thought I had was to liberally mark the code with performance.mark() statements and on an error dump the performance buffer to the server. It would give me an ordered list of recent activity.
However it only makes sense to do this if the browser throws away the oldest entry to make way for the new when the internal buffer is full. However all the documentation I found with a google search doesn’t mention it. I am aware I can get an event when it is full and could use that to copy and clear it but I can find no words on what happens if I ignore the event. Neither can I find a typical size. I don’t want to keep getting entries filling up the entire computer memory either
Can anyone give me a definite answer
Edit: The more I look into this, the more confused I become. It appears that you can control the size of the resourceTimingBuffer but "resource" performance entries are related to fetch and not Performance.mark(). I can't find any statement on limitations.
There are no meaningful limitations I could find. I did a test and generated more than 4000 marks and they were all there and the memory usage did not increase in any measurable way.
What the key value indicates.......and which is the term help me to undersatnd how the windbg bucket the crashes means how it braodly classify the crashes into?
help me to understand the windbg bucket
IMHO, the idea of buckets was introduced for WER (Windows Error Reporting). WER was used by Microsoft but was also available for companies. WER included a service where you could log in on a Microsoft website and then get an overview of your application crashes.
Of course, people were not interested in a flat list of crashes, but they wanted to know how many crashes of the same type occured. Thus Microsoft and other company could focus on fixing those bugs first which affected most of the users.
The bucket, as the name suggests, is a container where similar problems grouped. The bucket ID is generated in 2 phases: a labeling process which was done on the client side and a classifying process which was done on server side.
What you get from !analyze is the classification, so basically you have access to the functionality via WinDbg that Microsoft used on the server side for providing the WER services.
These WER services are not available any more. They hae been replaced by something else, but I have forgotten the name.
how it braodly classify the crashes into?
An ideal bucketing algorithm would create a new bucket for each bug. So the number of buckets is just limited by the amount of bugs you can code into your application.
The command !analyze has implemented more than 500 different heuristics. The combination of these can create more than 25.000.000 different buckets.
Buckets can differ because of
stack
modules
function name
function offset
corruptions (heap corruption, image corruption)
detected malware
known outdated programs or libraries
known defective hardware
exception codes
exception subcodes
...
The result of that bucketing process is this line of output:
FAILURE_BUCKET_ID: BREAKPOINT_80000003_ntdll.dll!LdrpDoDebuggerBreak
which is probably somehow equivalent to this hash:
FAILURE_ID_HASH: {06f54d4d-201f-7f5c-0224-0b1f2e1e15a5}
I have read some of your previous questions in the windbg tag and I get the impression that you want to use the bucket ID to display some meaningful information to humans.
Actually, the WER system provided such a feature. It worked like this: a developer analyzes the crashes in a bucket and finds out what to do (e.g. update a driver, install a newer version of the application etc). He then assigns that bucket ID a text. Any customers that experience the same crash again were redirected to a website at Microsoft that contained the text written by the developer.
However, note that there is no magic involved that would transfer a crash into something human readable. That's the developer doing hard work and then creating a mapping from the bucket ID to some text that is displayed.
IMHO, the latter can easily be achieved. However, any new bug will require an analysis first. But, who knows, maybe we can train an AI that does better at this.
For more on buckets etc. please read the Microsoft paper Debugging in the (Very) Large:Ten Years of Implementation and Experience
This feels something like an archeology expedition but I have been unable to find the record format of the first record of seemingly all executable load modules on z/OS systems. The record always starts with IEWPLMH even with when producing a GOFF format (which I have) runnable. Does anyone have any information on this or a link to it?
The format of load modules is documented in the Load Module Formats section of the z/OS MVS Program Management: Advanced Facilities manual.
But I suspect you are looking for the format of a program object, which is not documented, and, last I knew, IBM had stated they would not document (at least publicly for the likes of us).
There are decades of history behind this. IBM found themselves painted into a corner because customers had written code that depended on the format of load modules not changing. As of 2011, there were 8 different formats/subformats of program object and that number has no doubt grown. By not documenting (for customers) the format of a program object, IBM felt they had freed themselves to make format changes (adding features customers wanted) as they saw fit.
You may be able to get the information you want using the Binder's API or AMBLIST.
The use of the IEWBINDD facility is definitely the way to go. For USS programs,
When compiling the source, the -Wc,DLL option is required. When linking the -Wl,DYNAM=DLL does the trick. The example program in the appendix of the z/OS MVS Program Management: Advanced Facilities was very helpful.
I'm working on IBM MVS (z/OS) and trying to make Window Services working.
On the function CSREVW I don't understand what the purpose of the parameter pfcount.
Acording to the documentation this will ask to the window services to read more than one block after my program references a block that is not in my window.
But how the window services is suposed to know that I tried to reference data that are not in my window? I mean, it can't know that I'm reading data out of my window if i don't call CSREVW or CSRVIEW again.
Maybe my major issue is that I have trouble to understand english but this seems clear to me...
Here is the link to the documentation, this is explained at pages 23-24 :
http://publibz.boulder.ibm.com/epubs/pdf/iea3c102.pdf
I know this is a very specific problem about an IBM service and I apologize about that.
Thank you !
Tim
I think the problem you're having is that you need to understand a little bit about how the underlying objects behind the windowing service work in virtual storage.
At the core, the various windowing services work to give you what amounts to a "private" page dataset. You allocate and reference storage, but the objects in that virtual space aren't really in memory - the system's page fault mechanism brings them in as you reference them. So yes, you're accessing data within a "window", but in reality, the data you expect to see may not be "paged in" at that moment.
Going a little deeper, when you first allocate the object, the virtual storage it's mapped to has all of the pages marked "invalid" in the underlying page table entries. That means that as soon as you touch this storage, a page fault interrupt occurs. At this point, the operating system steps in and resolves the page fault by brining the necessary data into memory, then your program continues, oblivious to all of this processing on your behalf. You're correct that you're just referencing data within the window, but there's a lot under the covers going on to support this.
This is where PFCOUNT comes in...
Let's say you have structures that are, say, 64K long inside your virtual window. It would be sloppy and slow to reference each page of this structure and cause a page fault each time. Much better would be to use PFCOUNT to cause the page you reference and all 15 other pages needed by your object to be paged-in with a single operation. Conversely, if your data was small and you were highly random about how you access it, PFCOUNT isn't going to help you - the next page you reference could be anywhere, and it's actually wasteful to have a large PFCOUNT since you end up bringing in a lot of data you never use.
Hope that makes sense - if you'd like a challenge, take yourself a system dump and examine the system trace entries as you reference data...you'll see a very distinct pattern of page faults, I/O and resumption of your program, and hopefully it will all make sense to you.
From the manual
,pfcount
Specifies the number of additional blocks you want window services to bring into the window each time your program references data that
is not already in the window. The number you specify is added to the
minimum of one block that window services always brings in. That is,
if you specify a value of 20, window services brings in up to 21. The
number of additional blocks ranges from zero through 255.
Note that you get 1 block without asking.
I have a product that is basically a USB flash drive based on an NXP LPC18xx microcontroller. I'm using a library provided from the manufacturer (LPCOpen) that handles the USB MSC and the SD card media (which is where I store data).
Here is the problem: Internally the LPC18xx has a 64kB (limited by hardware) buffer used to cache reads/writes which means it can only cache up to 128 blocks(512B) of memory. The SCSI Write-10 command has a total-blocks field that can be up to 256 blocks (128kB). When originally testing the product on Windows 7 it never writes more than 128 blocks at a time but when tested on Linux it sometimes writes more than 128 blocks, which causes the microcontroller to crash.
Is there a way to tell the host OS not to request more than 128 blocks? I see references[1] to a Read-Block-Limit command(05h) but it doesn't seem to be widely supported. Also, what sense key would I return on the Write-10 command to tell Linux the write is too large? I also see references to a block limit VPD page in some device spec sheets but cannot find a lot of documentation about how it is implemented.
[1]https://en.wikipedia.org/wiki/SCSI_command
Let me offer a disclaimer up front that this is what you SHOULD do, but none of this may work. A cursory search of the Linux SCSI driver didn't show me what I wanted to see. So, I'm not at all sure that "doing the right thing" will get you the results you want.
Going by the book, you've got to do two things: implement the Block Limits VPD and handle too-large transfer sizes in WRITE AND READ.
First, implement the Block Limits VPD page, which you can find in late revisions of SBC-3 floating around on the Internet (like this one: http://www.13thmonkey.org/documentation/SCSI/sbc3r25.pdf). It's probably worth going to the t10.org site, registering, and then downloading the last revision (http://www.t10.org/cgi-bin/ac.pl?t=f&f=sbc3r36.pdf).
The Block Limits VPD page has a maximum transfer length field that specifies the maximum number of blocks that can be transferred by all the READ and WRITE commands, and basically anything else that reads or writes data. Of course the downside of implementing this page is that you have to make sure that all the other fields you return are correct!
Second, when handling READ and WRITE, if the command's transfer length exceeds your maximum, respond with an ILLEGAL REQUEST key, and set the additional sense code to INVALID FIELD IN CDB. This behavior is indicated by a table in the section that describes the Block Limits VPD, but only in late revisions of SBC-3 (I'm looking at 35h).
You might just start with returning INVALID FIELD IN CDB, since it's the easiest course of action. See if that's enough?