Would it be possible for the vmcp kernel driver to have an option to
pre-allocate some fixed size of contiguous memory and hold onto it? This would
prevent fragmentation which can hit you at any time. I remember using vmcp from
a Linux based installer which typically started by downloading
> I have problem with page allocation failure on SUSE Linux Enterprise Server
> 11 (s390x) VERSION = 11 PATCHLEVEL = 4
> Logs on messages:
> kernel: WebContainer : : page allocation failure: order:4, mode:0x4d0
> kernel: mount.nfs: page allocation failure: order:4, mode:0x4d0
When the kernel
I don't know if that changed but it used to be that zipl could safely boot from
LVM that was on only one physical volume. See this older discussion for details:
http://www.mail-archive.com/linux-390%40vm.marist.edu/msg62491.html
Tomas
Tomas Pavelka
CA Technologies
Sr Software Engineer
CA CZ,
I am assuming you want to do this from Linux and not from CMS. If I remember it
right, the DASD driver does not show you the entire device, only the data
portion of CKD and also not record 0. This means that if dasd has been once
formatted, Linux will try to access it as formatted drive.
There
Hi Neale,
I would guess that the issue is that the Maven repository is a different thing
than an RPM repository:
https://maven.apache.org/guides/introduction/introduction-to-repositories.html
I am also guessing there isn't anything that could turn the RPM repo to a Maven
repo, but I have not
The same Java class can be present in multiple JAR files in your class path
which may be a pain to debug. What I found helpful is to turn on class loading
tracing - add the "-XX:+TraceClassLoading" option.
This lets you know which exact location the class was loaded from.
It works in Oracle
I have used it successfully with FORMAT=NO. But this was in our proprietary
SMAPI library so I can't share. But the call is not complicated, just put
together function name, target and append FORMAT=NO. I am not familiar with
smaclient, but if you get to understand how it assembles the SMAPI
> Is this a known issue? I'm assuming it's SMAPI in the backend, not smaclient
> on the front end causing the slowness.
The best I can remember is that for a user directory with somewhere between
100-200 entries the Query_All_DM took 1-3 seconds. Most of the CPU was spent on
the SMAPI side,
I was once researching something similar (i.e. how to get reliable CPU readings
from within Linux) but unfortunately never finished. But I still have the
links, maybe you will find something interesting there:
Presentation about how Linux kernel can get accurate CPU readings from the
SourceForge R/W access has been offline for 4 days!!
Have you seen this?
https://www.reddit.com/r/sysadmin/comments/3do9k0/sourceforge_is_down_due_to_storage_problems_no_eta/
Tomas Pavelka
CA Technologies
Sr Software Engineer
CA CZ, s.r.o
V Parku 12,
148 00 Praha
Czech Republic
Office:
I wouldn't really put that at the feet of s390 (z/Architecture).
Bad wording on my part. When I said s390 I meant the s390 part of the Linux
kernel implementation, not the entire architecture. I meant to point out that
the other parts of the kernel are working on getting out of the requirement
the qeth driver has been improved in 2014 to reduce its demand for contiguous
storage:
Thanks Ursula, the memories keep coming back ;-) I remembered that the vmcp is
still problematic but managed to forget that the qeth driver got fixed.
Let me try a different example than Mike's 'Q DASD DETAILS 0-': Suppose you
are writing software for disaster recovery of LVM disks. The Linux that owned
them will not come up so you link them from another Linux. Get a list of
minidisk addresses and their owners and issue LINK against each.
I replied to Mike and Alan yesterday evening but it does not show in the
archives. I am assuming it got lost and I am resending. Sorry if this is a
duplicate.
If vmcp is called with a buffer of 1M and the last slab in
/proc/buddyinfo is 0, would it not be reasonable to nudge
the kernel to
Only admins would have access to those sudo commands.
But the sudoers line shows an intent to restrict access to tee only:
%zoom ALL=NOPASSWD:/usr/bin/tee
The hole that Karsten has shown is that the line in sudoers is really the
security equivalent of:
%zoom ALL=NOPASSWD:ALL
Whether it is a
As a workaround, is there a command to flush the buffer cache?
I forgot to answer this question: you can drop buffers and cache by running
echo 3 /proc/sys/vm/drop_caches
See http://linux-mm.org/Drop_Caches
As far as I remember this did not help at all. My guess about why that did not
help
. :-)
DJ
On 07/09/2015 07:50 AM, Pavelka, Tomas wrote:
Look at the -/+ buffers/cache line in the free output:
Before:
-/+ buffers/cache: 41450
After:
-/+ buffers/cache: 48443
(First number used, second free)
Linux has various buffers and caches
Thanks. I copied and pasted cmmflush and it seems to work nicely
If I understand it right then you have to look at how cmmflush affects the
output of /proc/buddyinfo. If you see non-zero in the last order of slab (i.e.
the one with 1MB size) then you are good to run vmcp --buffer=1M.
This is a really ugly problem that I don't have a solution for. But let me give
you a bit of info if you want to do your own digging:
The way I found this is that I was adding NICs to a Linux on the fly. Sometimes
this would fail, saying page allocation in syslog. The discussion on this list
The next question is - can this ever be done by a non-root user? I tried
adding /bin/echo to /etc/sudoers, but still get an error:
I was able to google these two approaches to dropping caches over sudo:
sudo sh -c sync; echo 3 /proc/sys/vm/drop_caches
or
echo 3 | sudo tee
Maybe I'll think about sudo-enabling cmmflush and checking the last field of
/proc/buddyinfo to see if it needs to be run.
I tried doing things based on the values of /proc/buddyinfo but what I found is
that if there are zeroes in the high order slab counts, there is a chance that
vmcp with
Look at the -/+ buffers/cache line in the free output:
Before:
-/+ buffers/cache: 41450
After:
-/+ buffers/cache: 48443
(First number used, second free)
Linux has various buffers and caches that are allocated if there is free
memory. For example for disk reads.
Do not include the root file system in the LVM structure because, if for any
reason the LVM
fails, the operating system will not boot. - Set up Linux on IBM System z
for Production
People often give non-unique names to volume groups. For example if you name
the VG root resides on RootVG
Hi Rob,
thanks for the reply. The performance of Linux under a second level VM always
seemed unpredictable to me but after reading your response I started seeing a
pattern: whenever I had a poorly performing application on Linux on a second
level VM, there was always some kind of networking
And because the optimizer uses elapsed time rather than cpu time it keeps
recompiling classes and kind of digs is own grave. You might try without the
optimizer on 2nd level Linux.
I wrote a simple benchmark that just prints a number of lines on the console.
Java uses about 180 times more
I have a Java application running a REST API built on top of the Dropwizard
stack (www.dropwizard.iohttp://www.dropwizard.io). I have been running it on
a first level z/VM and it was always well behaved consuming less than 1% of a
CPU on an EC12 during normal operation. I needed to do some
Is there a place within OMVS to find the ID being defined ? Is there a path
where get the list of ID defined within OMVS ?
Sorry, I assumed you are on Linux... I don't know much about USS.
Tomas
getent?
http://linux.die.net/man/1/getent
Examples:
getent passwd 99
nobody:x:99:99:Nobody:/:/sbin/nologin
getent passwd nobody
nobody:x:99:99:Nobody:/:/sbin/nologin
getent group nobody
nobody:x:99:
getent group 99
nobody:x:99:
HTH,
Tomas
I envision people using KVM on System z eventually deciding they want to
upgrade to z/VM for the better capabilities and manageability it provides.
Could you elaborate on what are the most important things that z/VM provides
that KVM does not? I occasionally get questions from people that
Use FOR to execute a CP command on another virtual machine and receive the
command's responses and return code either to your terminal or over an IUCV
connection to the Asynchronous CP Command Response system service (*ASYNCMD).
Not that you have the AF_IUCV support in Linux kernel so you can
Just to explain what I am trying to do: over the years I have been involved in
multiple discussions about installations that involved people supporting
different platforms. It is often difficult to convince everyone that RPM is the
right thing to do and that interactive installers are not a
Things like InstallMangler seem like good ideas to product owners since it
allows them to provide the illusion of a simplified install experience that
is common across all platforms
For the same product owners the opinions of (potential) customers often carry
more weight than those of a
Hello,
I am in the middle of discussion about how to package and install software on
Linux for System z. There are people new to Linux involved and things like
InstallAnywhere are coming up. What is your experience with non-RPM installers?
For example, IBM Java no longer comes in as RPM for the
[mailto:LINUX-390@VM.MARIST.EDU] On Behalf Of Pavelka,
Tomas
Sent: Tuesday, November 18, 2014 2:27 AM
To: LINUX-390@VM.MARIST.EDU
Subject: Re: device-mapper: reload ioctl on failed
It works if I attach the mini-disk was multi-write. This is not what we want
but it works. Any ideas?
A lot
It works if I attach the mini-disk was multi-write. This is not what we want
but it works. Any ideas?
A lot of speculation on my part follows. Again I will point to Red Hat as the
more informed party. The bug I dealt with before seems very similar to what you
are experiencing. There were
What version of the lvm RPM are you running? We have run into a problem on a
CentOS 6 installation where LVM would not put online disks that were read only.
The bug started at a version that I unfortunately forgot and was fixed in a
newer version that I forgot as well. But I managed to find one
lvm2-2.02.100-8.el6.s390x
When I was dealing with this I had a version that had the bug fixed and I think
it was older than 2.02.100. It was 2.02.9x something. I would guess that your
problem is LVM related but not the same that I had. Red Hat would give you
better advice than I do.
Tomas
Are you looking for documentation of the individual user directory statements?
That can be found in the IBM book CP Planning and Administration, in the
section Creating and Updating a User Directory
http://pic.dhe.ibm.com/infocenter/zvm/v6r3/topic/com.ibm.zvm.v630.hcpa5/cusrdir.htm
If you
warm bodies authenticate with PKI using a central LDAP store for public keys
Being curious, how do you deal with situations when LDAP is temporarily not
available?
Tomas
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Thanks everyone for the very insightful comments.
Tomas
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send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or visit
One way is to have standby memory defined.
For example, if you have user LINUX and want to have 512MB with the chance to
go up to 2G, then you add the 2G as max memory on the USER directory statement:
USER LINUX PASWD 512M 2048M G 64
Then add the following statement to the user directory to
Unless you want all your Linux machines to have four CPUs, you'd have to change
your profile. There is this line in the doc of the CPU directory statement:
If specified, the CPU statement must appear before any device statements.
Since you have NICDEF in your profile, you can't put CPU
There are no conditions in which a CPU's type is unknown. Rather, it's a bug
in hyptop.
If anyone actually tries to use this, note that the version of hyptop I was
running is quite old. I did not test whether newer versions fix this behavior.
There must be some way to determine. At least when using hyptop in LPAR, it
tells the number of available IFL and CP in the top line.
I have looked at the source of hyptop and it reads the information from
debugfs, namely from these two files:
/sys/kernel/debug/s390_hypfs/diag_204 - if
An interesting alternative to this is to mount by label, here is an example of
fstab lines:
LABEL=root/ ext3defaults1 1
LABEL=usr /usrext3defaults0 0
Before you can mount by label, you need to put the label on the file
'NR 2 {split($5,a,:);
One thing you should watch out for is that the IP address could be an IPv6. In
that case, you cannot split by : because there may be many : in the
address. So you would need something that parses out the number after the last
colon in field 5. But I'm not really good
Not sure if this is the root cause of your problem, but zipl does not support
booting from a logical volume consisting of more than one physical volume. It
may work in some cases but is generally unsafe. Previous discussion is here:
Thanks for all the replies. I did not fully explain what I'm doing before
detach so let me make that clearer. To offline and detach a NIC I do the
following:
1) Write 0 to /sys/bus/ccwgroup/devices/busid/online
2) Wait for /sys/bus/ccwgroup/devices/busid/online to become 0 and for
Does writing to ungroup synchronously generate a udev event?
To generate the event synchronously, the write to the file would have to block
until the udev event is generated. I don't think it is the case, but I have not
actually tried/researched.
I have a script that dynamically adds and removes virtual NICS. E.g. it runs
define nic, couples it to a vswitch, sets it online, connects somewhere, sets
it offline, ungroups and detaches it.
The problem I have is that I cannot figure out how to tell that the device is
really offline and the
When setting the MACPROTECT ON at the NIC level, the vdev specified must be
that of the data device. This is probably A002 in your case.
That did the trick in both cases. Thanks!
Tomas
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I would like to use MACPROTECT ON for Linux guests on a vswitch but it is not
working as I would expect. My understanding is that MACPROTECT ON will not
allow a NIC to send a frame with source mac address different from the one
assigned by CP.
I have a Linux bridge that bridges layer 2 traffic
What we do to speed dasdfmt up is to split the large dasd into smaller
minidisks and join them by LVM. Then the individual minidisks can be formatted
in parallel. This is easy to script with xargs, which has the parameter
--max-procs that lets you specify the maximum number of worker processes
I gave up and looked at some code. :-) The x200C is generated when you try
to register a universal MAC address or one that potentially conflicts with a
MAC address CP might create.
That means you can only register additional MAC addresses that have MAC
prefixes that are outside the range
We have done more research and found out that the same problem as we have is
faced by virtualization software running under Linux. I have found a discussion
about a feature called secondary unicast address that would allow registering
multiple MAC addresses with a NIC. Here is a discussion that
I was talking to Carsten and he said that the MAC address gets registered with
the OSA card via calls from the Linux kernel drivers. He also mentioned that
KVM faces the same problem. We will attempt to do the registering of the extra
MAC addresses from a kernel module running on the bridge
so you must be performing MAC address translation such that you look more
like a a layer 2 router (a la OSA in layer 3 mode),
not an 802.1d bridge (I said 802.3 earlier; I meant 802.1d.) That is, all
guests on the PUBLIC vswitch have the same MAC
address as viewed by all hosts on the
We have a problem where frames that pass through a Linux bridge do not reach
the gateway outside of the mainframe box. We have set up an experiment that
reproduces the problem, which looks like this:
(LINUX1) - private vswitch - (LINUXBR) - public vswitch - OSA - gateway
The problem is that in
Thanks, this means a big change to our plans ;-) Do you know if there are any
public docs (or source code) that we could look at to understand how the
negotiation works?
Tomas
-Original Message-
From: Linux on 390 Port [mailto:LINUX-390@VM.MARIST.EDU] On Behalf Of Carsten
Otte
Sent:
Another question that comes to mind is, if there is negotiation with OSA, how
does Linux tell that there is a real OSA involved? My assumptions (which may be
false ;-)) were that Linux as a z/VM guest should not be able to tell whether a
NIC is real or virtual. And in our case the NIC is always
What is LINUXBR doing for you that the VSWITCH cannot do for you?
We are in the business of porting software that works on top of a Linux bridge.
We have a kernel driver that hooks into the Linux bridge and filters layer 2
frames based on rules. We got it working on Xen, VMware and inside z/VM
Further, the VSWITCH is already acting as an IEEE 802.3 layer 2 bridge and
its filtering database will drop unicast frames destined for unknown MAC
addresses.
One thing I forgot to mention: We have successfully sent packets between two
vswitches connected to a Linux bridge (LINUX1 and
so you must be performing MAC address translation such that you look more like
a a layer 2 router (a la OSA in layer 3 mode), not an 802.1d bridge (I said
802.3 earlier; I meant
802.1d.) That is, all guests on the PUBLIC vswitch have the same MAC address
as viewed by all hosts on the PRIVATE
Are you planning to run the RTC server or clients? I have no experience with
the server but have been running a client for a few years. For the client, only
command line runs on zLinux (i.e. no Eclipse). The CLI runs fine with 512M of
memory.
Tomas
-Original Message-
From: Linux on
Does anyone know a freeware graphics tool that could somehow reverse-video,
or just brighten these graphics? They are all GIFs (pronounced JIFs :))
How about ImageMagick?
http://www.imagemagick.org/Usage/color_basics/#replace
RPMs exist for s390x, at least for RHEL they are part of the
The main problem is not the huge amount of errors in the syslog. The main
problem is the contention caused by the locate record ccws that end up in
error. I have seen this happen anytime there are counts with the wrong cylinder
anywhere on the disk and the first cylinder of the disk is in
One error message is ignorable. Hundreds are a problem that should be
fixed.
I just had to learn this the hard way... I started playing with
raw_track_access, noticed the large number of I/O errors reported, but paid it
no mind and made it work. I wrote a CKD track that was not recognized as
Excuse my ignorance, but what is FBAF?
This is a minidisk definition in the user directory:
MDISK FBAF 3390 4819 1000 VMBL2H WR
FBAF is the virtual address of the disk.
When we first ran into this, we were doing experiments and weren't sure if we
are able to reproduce the problem. But we had
Thanks for the replies, here are my thoughts on the problem:
I agree that before a minidisk is given to a guest (before the guest is started
for the first time) the minidisk needs to be formatted and any data that was
previously on the disk erased. The question is, when to do it and from which
when running normal dasdfmt so
this is nothing new.
Tomas
-Original Message-
From: Stefan Haberland [mailto:s...@linux.vnet.ibm.com]
Sent: Wednesday, March 13, 2013 5:20 PM
To: Linux on 390 Port
Cc: Pavelka, Tomas
Subject: Re: DASD format from Linux only
Hi Tomas,
I have a possible
We have been trying to format all minidisks from Linux only and this turned out
to be problematic. I am looking for a solution that would let us stay in Linux
without having to involve CMS format for every new minidisk. Let me first
describe the problem:
When there is a record on dasd that has
If it helps I have done the following experiment: Added a new minidisk to the
guest with LVM and ext2 on it at vaddr 204 and added the following udev rule:
/etc/udev/rules.d/51-dasd-0.0.0204.rules
ACTION==add, SUBSYSTEM==ccw, KERNEL==0.0.0204, IMPORT{program}=collect
0.0.0204 %k 0.0.0204
|grep ${DEVPATH##*.}|grep -q R/O',
ATTR{readonly}=1
Again...make sure it's all on one line.
Leland
On 2/13/2013 1:31 AM, Pavelka, Tomas wrote:
Will your solution preserve read only attributes? I.e. if you bring all dasd
online with a single udev rule, will those linked as read only have
A minidisk is a continuous range of cylinders on a real disk, that the guest
sees as a virtual disk. For example, the meaning of this:
MDISK 700 3390 0001 10016 MM2101
700 - this is the virtual address of the minidisk as seen by the Linux guest
3390 - this is the type of the real disk that the
Will your solution preserve read only attributes? I.e. if you bring all dasd
online with a single udev rule, will those linked as read only have the correct
read only attributes so the kernel knows that it cannot write to them?
Example of what I mean by correct read only attributes:
vmcp q v
The internal bash parameter expansion functions (e.g. ${line%% *}) tend to be
quite inefficient. Here is one example, compare the performance of bash
substitution to Perl substitution:
#!/bin/bash
comma_sep=$(perl -e 'for($i=0;$i1000;$i++) { print($i;) };')
time space_sep=${comma_sep//;/ }
time
I have recently run a similar experiment measuring how fast do various disk
operations run. Although I haven't attempted to compare dd with dasdfmt and the
variation is high, here are the most commonly seen numbers:
dasdfmt + pvcreate : 30-40 MB/s
dd : 30-80 MB/s
dasdfmt + pvcreate, parallel
Hello,
Does anyone have experience with booting from an LVM device that spans multiple
physical disks? This presentation:
https://share.confex.com/share/118/webprogram/Handout/Session10310/System%20z%20Roadmap%20SHARE%202012.pdf
Says that it is possible:
zipl bootloader supports device-mapper
Is there a known reliable workaround? I have tried running dasdfmt in a script
right after chccwdev and run into the non-existent device problem. So I tried
putting a loop after chccwdev waiting for the device to appear in /dev, like
this:
while [[ ! -b $dev ]] ; do
sleep 0.1
done
and
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