[Xymon] [External] Memory leak in Windows Virtual Disk service caused by Xymon Windows Powershell client

[SebA]

 Hi Zak,

Thanks for your swift reply and sorry for my own delay!  It's good to know
you have such extensive use of the PS client without this issue.

I think you are probably right.  These issue has only appeared on servers
using Windows Cluster Failover, where various iSCSI disks are clustered.

For the record, my workaround of disabling the Virtual Disk Service caused
no bad effects on the server, but it does prevent diskpart from running.  I
set the service back to Manual, and it started as soon as I ran diskpart
from an elevated Command Prompt.  Exiting diskpart causes the VDS service
and proces to stop.

When the Virtual Disk Service was set to manual, and started just by me
running diskpart.exe, the client output has:

[diskpart]
diskpart:::Clustered Unknown

When the service is disabled, the output is just an empty section:

[diskpart]

When VDS is started by me restarting the XymonPSclient service and it being
on manual, the output is e.g.:

[diskpart]
diskpart:Disk 0:278 GB:Not Clustered
diskpart:Disk 1:1024 MB:Clustered Active
diskpart:Disk 2:25 GB:Clustered Active
diskpart:Disk 3:500 GB:Clustered Active
diskpart:Disk 4:300 GB:Clustered Inactive
diskpart:Disk 5:1024 MB:Clustered Inactive
diskpart:Disk 6:500 GB:Clustered Inactive
diskpart:Disk 7:200 GB:Clustered Inactive
diskpart:Disk 8:1024 MB:Clustered Inactive
diskpart:Disk 9:1024 MB:Clustered Inactive
diskpart:Disk 10:200 GB:Clustered Inactive
diskpart:Disk 11:200 GB:Clustered Inactive
diskpart:Disk 12:500 GB:Clustered Active
diskpart:Disk 13:5120 MB:Clustered Active
diskpart:Disk 14:500 GB:Clustered Inactive

Compared with VDS running because of me running diskpart and running:

“list disk”

For each disk returned, “select disk {n}” and then “detail disk”

for each disk (which does not leak memory) vds.exe uses about an extra MB
of RAM when running due to the PS client.

I have also now commented out the line you suggest (' $script:diskpartData
= XymonDiskPart ') and now when I restart the XymonPSclient service with
VDS set to Manual it does not get restarted and left running (or restarted
at all).  So this looks like a better workaround than just disabling the
service, but I will need to continue to monitor that.

Is the XymonDiskPart information used for anything?  I mean, can it be used
for anything without writing plug-ins?

We do not have memory leaks in powershell.exe on these servers (although I
think I may have seen it on another server), so the issue above is not
related to Alessandro's issue.

Thanks again for your help Zak, and I hope this knowledge is of benefit to
you or others too.


Kind regards,

SebA


On 14 March 2018 at 09:21, Beck, Zak <zak.beck at accenture.com> wrote:

> Hi Seb
>
>
>
> I’ve got hundreds of VMs running the Powershell client on Windows Server
> 2008R2, 2012R2 and 2016 and I don’t see this issue. I just checked a couple
> of servers, vds.exe is between 2MB and 20MB and around 21 threads. Same
> version of vds.exe too.
>
>
>
> I’m wondering if function XymonDiskPart has something to do with it. This
> only runs on slow scans (every 6 hours-ish by default). This runs
> ‘diskpart’ and then
>
>
>
> “list disk”
>
> For each disk returned, “select disk {n}” and then “detail disk”
>
>
>
> Maybe you could try this from the command prompt on a server with vds
> stopped and see if it restarts it. You could also try commenting out this
> line (3875, towards the end) in the client and see what happens (insert a #
> at the beginning of the line):
>
>
>
>         $script:diskpartData = XymonDiskPart
>
>
>
>
>
> Alternatively, it could be the disk utilisation code which is using
> Windows API calls in kernel32.dll – FindFirstVolume, FindNextVolume,
> FindVolumeClose, GetVolumeInformation, GetVolumePathNamesForVolumeNameW,
> GetDiskFreeSpaceEx and GetDriveType. The MSDN documentation for these
> doesn’t mention the Virtual Disk Service but I guess they could be using it.
>
>
>
> Zak
>
>
>
> *From:* SebA [mailto:spah at syntec.co.uk]
> *Sent:* Tuesday, 13 March 2018 18:14
> *To:* Beck, Zak <zak.beck at accenture.com>; Xymon Mailing List <
> xymon at xymon.com>
> *Subject:* [External] Memory leak in Windows Virtual Disk service caused
> by Xymon Windows Powershell client
>
>
>
> I have noticed a memory and thread leak in the Windows Virtual Disk
> service - or vds.exe from the process list.  This service is set to Manual
> by default and gets started when starting the XymonPSClient service on
> Windows 2008 R2.  It starts off using 32 threads, but grows forever, the
> virtual memory and physical memory (which starts under 6 MB) used slowly
> grow too.
>
> Has anyone noticed this problem and do they have a solution to it?
>
> On Windows Server 2012, the Virtual Disk service does not get started by
> Xymon Windows Powershell client, so it's obviously not started directly by
> the client, but by a request for information.  I looked into known memory
> leaks for vds.exe and the one I found was not applicable to 2008 R2, only
> 2008 and Vista.  The version of vds.exe we have is later than the version
> with the fix: 6.1.7601.17514 from 2010.
>
> The quick workaround is simply to stop the Virtual Disk Service - but as
> soon as the PSclient has used it, it does not stop properly and terminates
> unexpectedly, so one needs to set it not to restart on crash, or stop it
> immediately after starting, or to Disabled.  But it would be good to know
> why it is starting, not stopping, and leaking threads / memory!
>
>
> Kind regards,
>
> SebA
>
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