FOG 1.5.6: Auto resize is unpredictable

[george1421]

@Eric-Johnson While you are way over my head with this coding, I can make a suggestion that may make debugging faster.

1. If you create a /images/dev/postinit script, you can patch (copy over from the FOG server to FOS) /usr/share/fog/lib/partition-funcs.sh on every boot of FOS. You don’t need to unpack and repack the inits. There is an example in the forum on how to patch (replace) fog.man.reg for a custom registration. ref: https://forums.fogproject.org/topic/9754/custom-full-host-registration-for-1-3-4/45

2. At the FOS Linux command prompt, if you give root a password with passwd (just some simple password like hello) and then get the IP address of FOS with ip addr show you can connect to FOS via putty/ssh from a second computer. Of course you need to be in debug mode to do this, but with putty you can copy/paste/debug from your normal workstation.

[Sebastian Roth]

@Eric-Johnson I think you are doing a really great job here trying to nail this down. I’d love to help you but as I can’t replicate the issue same as you can I can only assist with commenting here in the forum. The checks you added seem appropriate! Let’s try to get even more output and see what we find. Remove the output redirection in line 76 of /usr/share/fog/lib/partition-funcs.sh:

applySfdiskPartitions() {
    local disk="$1"
    local file="$2"
    [[ -z $disk ]] && handleError "No disk passed (${FUNCNAME[0]})\n   Args Passed: $*"
    [[ -z $file ]] && handleError "No file to receive from passed (${FUNCNAME[0]})\n   Args Passed: $*"
    sfdisk $disk < $file
    [[ ! $? -eq 0 ]] && majorDebugEcho "sfdisk failed in (${FUNCNAME[0]})"
}

[Eric Johnson]

So… current status.

Since it worked all the time with my diff with a Pause I just removed my Pause in non-debug mode… Seriously.

I have done 6 multicast deploys to 4 machines with this init and had no resize problems. Running with the original init showed 1-2 out of 4 resize failures.

This of course is NOT what I would call a fix. Kinda a workaround. And I don’t know if this is fixing the problem or just making it less likely to happen, as this should not be actually fixing anything. I through it out here for folks who might run into the same problem as a workaround till we figure out what the hell is going on…

diff -u /mnt/init-orig/usr/share/fog/lib/partition-funcs.sh /mnt/init/usr/share/fog/lib/partition-funcs.sh
--- /mnt/init-orig/usr/share/fog/lib/partition-funcs.sh 2019-05-04 17:58:07.000000000 -0400
+++ /mnt/init/usr/share/fog/lib/partition-funcs.sh      2019-07-11 09:22:49.000000000 -0400
@@ -401,8 +401,15 @@
     #    majorDebugPause
     #fi
     #[[ $status -eq 0 ]] && applySfdiskPartitions "$disk" "$tmp_file1" "$tmp_file2"
+    processSfdisk "$minf" filldisk "$disk" "$disk_size" "$fixed" "$orig" 
+#        Pause ESJ
     processSfdisk "$minf" filldisk "$disk" "$disk_size" "$fixed" "$orig" > "$tmp_file2"
     status=$?
+       echo $tmp_file2
+       ls -l $tmp_file2
+        cat $tmp_file2
+#        Pause ESJ
+
     if [[ $ismajordebug -gt 0 ]]; then
         echo "Debug"
         majorDebugEcho "Trying to fill with the disk with these partititions:"

[Eric Johnson]

@Sebastian-Roth Doh. Good idea, should have thought of that. But since even just doing some other output (see my recent post) seems to make the problem vanish…

Dis one is very odd.

[Quazz]

I created a PR to fix some stuff and to hopefully handle errors better/more reliably.

I don’t think it will fix this problem necessarily, but it should should hopefully throw errors when we expect it to.

https://github.com/FOGProject/fos/pull/26

You can download the inits of it here: https://dev.fogproject.org/blue/organizations/jenkins/fos/detail/PR-26/2/artifacts

if you’re interested in testing it out.

[Quazz]

@Eric-Johnson Interesting. Could you add

cat /proc/sys/kernel/random/entropy_avail

before and after your output commands?

Just a wild hunch

If my hunch is correct, then I suspect you could replace your output commands with any other output commands and it would work. Alternatively, you could smash the keyboard a couple of times.

[Eric Johnson]

@Quazz That was a crazy brilliant idea!

I did the below, first cat before anything, then the processSfdisk to the screen then a second cat, then a pause so I can read it and it probably wasn’t important at that point (I think that would have shown the entropy increase, please let me know if I am miss-understanding what you wanted to see) but on two unicast tests so far… 2260 before / 2261 after (identical)

Going to do a multicast test to all 4 in a sec. See if there is any variation.

diff -u /mnt/init-orig/usr/share/fog/lib/partition-funcs.sh /mnt/init/usr/share/fog/lib/partition-funcs.sh
--- /mnt/init-orig/usr/share/fog/lib/partition-funcs.sh 2019-05-04 17:58:07.000000000 -0400
+++ /mnt/init/usr/share/fog/lib/partition-funcs.sh      2019-07-11 15:31:10.000000000 -0400
@@ -401,8 +401,19 @@
     #    majorDebugPause
     #fi
     #[[ $status -eq 0 ]] && applySfdiskPartitions "$disk" "$tmp_file1" "$tmp_file2"
+cat /proc/sys/kernel/random/entropy_avail
+    processSfdisk "$minf" filldisk "$disk" "$disk_size" "$fixed" "$orig" 
+echo "after"
+cat /proc/sys/kernel/random/entropy_avail
+
+        Pause #ESJ
     processSfdisk "$minf" filldisk "$disk" "$disk_size" "$fixed" "$orig" > "$tmp_file2"
     status=$?
+       echo $tmp_file2
+       ls -l $tmp_file2
+        cat $tmp_file2
+#        Pause ESJ
+
     if [[ $ismajordebug -gt 0 ]]; then
         echo "Debug"
         majorDebugEcho "Trying to fill with the disk with these partititions:"

[Eric Johnson]

@Quazz grrr. no luck. entropy started pretty high and was only slightly higher after the call to processSfdisk in 8 out of 8 cases… 2258-2261 before and after in all cases.

Was a great idea, worth trying though!

[Eric Johnson]

Current status:

Tried clever suggestion from @Quazz … it didn’t pan out.

But inspired me to think outside the box. Tried using /root/sfblahblah.$$ instead of /tmp (since tmpfs is different than ramdisk…) That was just as unsuccessful.

Just adding a “sync;sync;sync” (cause anything I tell you three times is true) seems successful. On two tests so far.

Maybe?

Current working diff…

[root@fog ipxe]# diff -u /mnt/init-orig/usr/share/fog/lib/partition-funcs.sh /mnt/init/usr/share/fog/lib/partition-funcs.sh
--- /mnt/init-orig/usr/share/fog/lib/partition-funcs.sh	2019-05-04 17:58:07.000000000 -0400
+++ /mnt/init/usr/share/fog/lib/partition-funcs.sh	2019-07-11 18:10:20.000000000 -0400
@@ -401,8 +401,17 @@
     #    majorDebugPause
     #fi
     #[[ $status -eq 0 ]] && applySfdiskPartitions "$disk" "$tmp_file1" "$tmp_file2"
+#    processSfdisk "$minf" filldisk "$disk" "$disk_size" "$fixed" "$orig" 
     processSfdisk "$minf" filldisk "$disk" "$disk_size" "$fixed" "$orig" > "$tmp_file2"
     status=$?
+sync;sync;sync
+#	echo $tmp_file2
+#	ls -l $tmp_file2
+#        cat $tmp_file2
+#echo "after"
+#cat /proc/sys/kernel/random/entropy_avail
+#Pause #ESJ
+	
     if [[ $ismajordebug -gt 0 ]]; then
         echo "Debug"
         majorDebugEcho "Trying to fill with the disk with these partititions:"
[root@fog ipxe]#

[Tom Elliott]

@Eric-Johnson what about replacing sync with sleep 5? Sync is just ensuring cached items in wait get pushed to disk, maybe the scripts are working just a slight bit too fast?

[Sebastian Roth]

@Tom-Elliott While you might be pointing to the right spot here I don’t thing adding a time based sleep is a great idea.

[Quazz]

@Eric-Johnson I mostly wanted to see it before and after your cat and ls commands and such, but I don’t think it matters, since 2000+ should be more than enough for just about anything anyway.

I was thinking that perhaps certain hardware wouldn’t generate enough entropy in time and that that would cause issues.

@Sebastian-Roth @Tom-Elliott Do you reckon it would be good idea to try and store the output in a variable as opposed to a file and use it as such?

[Sebastian Roth]

@Quazz While I am not against your idea of trying to move this from file to variable I really wonder why we see this issue right here lately. Did we always have this issue and people just didn’t report? I doubt that! Or is it a change we pushed out in the last weeks? I have gone through the commit and nothing really makes sense from my point of view.

I just try to take one step back before we head into trying to fix this. Is this hardware specific? @Eric-Johnson
Should we try a 1.5.5 or even 1.5.4 FOG server and see if it’s the same?!

[Quazz]

@Sebastian-Roth From what I gather, it’s an issue that isn’t happening under every circumstance (personally haven’t ran into it, having deployed to hundreds of devices over the course of each new init release), but does happen reliably under certain conditions.

It seems odd that a momentary delay in the script or otherwise a sync of the “disk” (as in the ramdisk) would prevent this issue from appearing again.

From what I can tell, people did start reporting such issues after a certain version, perhaps a buildroot update (Just looked and Buildroot version 2019.02 has bugfixes up to 2019.02.4 now! changes list: https://git.busybox.net/buildroot/plain/CHANGES?id=2019.02.4) ? People tend to wait a while before updating, so we may have to look a bit further back.

[Eric Johnson]

Bad news. On the 3rd deploy with sync;sync;sync one failed.

Good news:

I moved all the metering to AFTER the sfdisk (and didn’t send the sfdisk output to /dev/null as was suggested by @Sebastian-Roth ). Found something interesting. Twice on one of the 4 machines the sfdisk is failing with a disk in use error. The input is good, no issue with the tmp file. But sfdisk seems to think the disk is in use. I think we have the smoking gun.

Adding some df and swapon -s now to see if this I can see the disk in use by some other tools. Next step if to dig up sfdisk source and see what makes it think it is use.

Maybe --force or --no-reread as suggested by the error mesage as a BFMI workaround?

--- /mnt/init-orig/usr/share/fog/lib/partition-funcs.sh 2019-05-04 17:58:07.000000000 -0400
+++ /mnt/init/usr/share/fog/lib/partition-funcs.sh      2019-07-12 08:37:10.000000000 -0400
@@ -73,7 +73,14 @@
     local file="$2"
     [[ -z $disk ]] && handleError "No disk passed (${FUNCNAME[0]})\n   Args Passed: $*"
     [[ -z $file ]] && handleError "No file to receive from passed (${FUNCNAME[0]})\n   Args Passed: $*"
-    sfdisk $disk < $file >/dev/null 2>&1
+#    sfdisk $disk < $file >/dev/null 2>&1
+    sfdisk $disk < $file 
+echo " "
+echo $file
+ls -l $file
+cat $file
+Pause #ESJ
+
     [[ ! $? -eq 0 ]] && majorDebugEcho "sfdisk failed in (${FUNCNAME[0]})"
 }
 # $1 is the name of the disk drive
@@ -403,6 +410,8 @@
     #[[ $status -eq 0 ]] && applySfdiskPartitions "$disk" "$tmp_file1" "$tmp_file2"
     processSfdisk "$minf" filldisk "$disk" "$disk_size" "$fixed" "$orig" > "$tmp_file2"
     status=$?
+#Pause #ESJ
+
     if [[ $ismajordebug -gt 0 ]]; then
         echo "Debug"
         majorDebugEcho "Trying to fill with the disk with these partititions:"

[Quazz]

@Eric-Johnson Very interesting, here’s what sfdisk man page has to say about it.

sfdisk uses BLKRRPART (reread partition table) ioctl to make sure
       that the device is not used by system or another tools (see also
       --no-reread).  It's possible that this feature or another sfdisk
       activity races with udevd.  The recommended way how to avoid possible
       collisions is to use exclusive flock for the whole-disk device to
       serialize device access.  The exclusive lock will cause udevd to skip
       the event handling on the device.  For example:

              flock /dev/sdc sfdisk /dev/sdc

       Note, this semantic is not currently supported by udevd for MD and DM
       devices.

So perhaps adding flock $disk before sfdisk $disk < $file will resolve it

Making the line read as flock $disk sfdisk $disk < $file

[Eric Johnson]

@Quazz

Reading the man page eh? Silly me downloading util-linux and tracing through source… LOL. (Hadn’t really started that except the download part )

Three times with flock $disk sfdisk $disk < $file now, no resize errors.

Gonna remove all the debug code and let em run to completion now.

I think ya got it though! Thanks!

[Tom Elliott]

This is really good information. I suppose it could be useful especially with the speed of NVMe usurping so many other disk access things, maybe udev is the issue the whole time in regards to “sporadic access” and usability?

Thank you all for the debugging and communication.

[Eric Johnson]

Two 4 stations multicasts. No resize problems. Below diff is only change. I think this one is done!

diff -u /mnt/init-orig/usr/share/fog/lib/partition-funcs.sh /mnt/init/usr/share/fog/lib/partition-funcs.sh 
--- /mnt/init-orig/usr/share/fog/lib/partition-funcs.sh 2019-05-04 17:58:07.000000000 -0400
+++ /mnt/init/usr/share/fog/lib/partition-funcs.sh      2019-07-12 10:26:47.000000000 -0400
@@ -73,7 +73,7 @@
     local file="$2"
     [[ -z $disk ]] && handleError "No disk passed (${FUNCNAME[0]})\n   Args Passed: $*"
     [[ -z $file ]] && handleError "No file to receive from passed (${FUNCNAME[0]})\n   Args Passed: $*"
-    sfdisk $disk < $file >/dev/null 2>&1
+    flock $disk sfdisk $disk < $file >/dev/null 2>&1
     [[ ! $? -eq 0 ]] && majorDebugEcho "sfdisk failed in (${FUNCNAME[0]})"
 }
 # $1 is the name of the disk drive

[Eric Johnson]

Found a couple more sfdisk that might need protecting…

[root@fog ipxe]# diff -ur /mnt/init-orig/usr/share/fog/lib /mnt/init/usr/share/fog/lib
diff -ur /mnt/init-orig/usr/share/fog/lib/funcs.sh /mnt/init/usr/share/fog/lib/funcs.sh
--- /mnt/init-orig/usr/share/fog/lib/funcs.sh   2019-05-04 17:58:07.000000000 -0400
+++ /mnt/init/usr/share/fog/lib/funcs.sh        2019-07-12 12:57:23.000000000 -0400
@@ -1977,7 +1977,7 @@
         sfdiskLegacyOriginalPartitionFileName "$imagePath" "$disk_number"
         if [[ -r $sfdiskoriginalpartitionfilename ]]; then
             dots "Inserting Extended partitions (Original)"
-            sfdisk $disk < $sfdiskoriginalpartitionfilename >/dev/null 2>&1
+            flock $disk sfdisk $disk < $sfdiskoriginalpartitionfilename >/dev/null 2>&1
             case $? in
                 0)
                     echo "Done"
@@ -1988,7 +1988,7 @@
             esac
         elif [[ -e $sfdisklegacyoriginalpartitionfilename ]]; then
             dots "Inserting Extended partitions (Legacy)"
-            sfdisk $disk < $sfdisklegacyoriginalpartitionfilename >/dev/null 2>&1
+            flock $disk sfdisk $disk < $sfdisklegacyoriginalpartitionfilename >/dev/null 2>&1
             case $? in
                 0)
                     echo "Done"
diff -ur /mnt/init-orig/usr/share/fog/lib/partition-funcs.sh /mnt/init/usr/share/fog/lib/partition-funcs.sh
--- /mnt/init-orig/usr/share/fog/lib/partition-funcs.sh 2019-05-04 17:58:07.000000000 -0400
+++ /mnt/init/usr/share/fog/lib/partition-funcs.sh      2019-07-12 10:26:47.000000000 -0400
@@ -73,7 +73,7 @@
     local file="$2"
     [[ -z $disk ]] && handleError "No disk passed (${FUNCNAME[0]})\n   Args Passed: $*"
     [[ -z $file ]] && handleError "No file to receive from passed (${FUNCNAME[0]})\n   Args Passed: $*"
-    sfdisk $disk < $file >/dev/null 2>&1
+    flock $disk sfdisk $disk < $file >/dev/null 2>&1
     [[ ! $? -eq 0 ]] && majorDebugEcho "sfdisk failed in (${FUNCNAME[0]})"
 }
 # $1 is the name of the disk drive