File server vault replication fails with NFS mount timeout errors under heavy load

PLM Windchill
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1

Hi all,

We’re running Windchill 11.2 M030 in a multi-site setup with two file server vaults — one primary vault (US-East) and one replica vault (EU-West). Both vaults are backed by NFS-mounted storage from our enterprise NAS.

Under normal load replication works fine, but when we have large CAD checkin bursts (50+ Creo assemblies simultaneously), vault replication starts failing with the following errors in the MethodServer logs:

[ERROR] com.ptc.windchill.enterprise.replication.ReplicationAgent - Replication job failed for vault EU-West-Vault
java.io.IOException: NFS stale file handle / timeout after 30000ms
    at com.ptc.windchill.fileserver.VaultFileTransfer.transferChunk(VaultFileTransfer.java:412)
    at com.ptc.windchill.enterprise.replication.ReplicationWorker.run(ReplicationWorker.java:187)

Our current wt.properties settings for replication:

wt.fv.replication.threadCount=4
wt.fv.replication.retryCount=3
wt.fv.replication.retryDelay=5000
wt.fv.replication.socketTimeout=30000

The NAS team says the NFS mount is healthy and there’s no storage-side timeout. I suspect it might be thread pool saturation or the socket timeout being too aggressive under load. Has anyone dealt with this specific pattern? We’re also wondering if the vault replication queue configuration in site.xconf needs tuning. Any pointers would be greatly appreciated.

system 2

Happy to give you a comprehensive answer based on what everyone has surfaced so far, because this is a well-known interaction between Windchill vault replication and NFS under load.

Root Cause Summary: You have a three-layer mismatch: (1) NFS client timeout too low, (2) Windchill socket timeout not aligned with NFS behavior, and (3) replication thread pool and queue saturation amplifying both issues.

Step 1 — Fix NFS Mount Options (highest priority) Edit /etc/fstab on the EU-West file server host:

naseu:/vaults/windchill /mnt/wc_vault nfs rw,hard,intr,timeo=600,retrans=5,rsize=1048576,wsize=1048576,actimeo=60,noatime 0 0

Key changes:

  • timeo=600 → 60-second base timeout (units are 0.1s)
  • retrans=5 → 5 retransmits before escalating
  • rsize/wsize=1048576 → 1MB read/write blocks for CAD file efficiency
  • actimeo=60 → reduces attribute cache invalidation churn under concurrent access
  • noatime → eliminates unnecessary write traffic for access time updates

Remount without rebooting: umount /mnt/wc_vault && mount /mnt/wc_vault

Step 2 — Update wt.properties on Primary MethodServer

wt.fv.replication.socketTimeout=180000
wt.fv.replication.threadCount=8
wt.fv.replication.retryCount=5
wt.fv.replication.retryDelay=15000
wt.fv.replication.chunkSize=8388608

Notes:

  • socketTimeout=180000 → 3 minutes, aligned above your NFS hard-mount ceiling
  • threadCount=8 → doubles concurrency but stay below 25% of your MethodServer max threads
  • chunkSize=8388608 → 8MB chunks drastically reduce NFS round-trips for large Creo files
  • retryDelay=15000 → gives NFS time to recover between retries

Step 3 — Tune ReplicationQueue in site.xconf Locate your site.xconf (typically $WT_HOME/codebase/WEB-INF/conf/site.xconf) and add/modify:

<Service name="wt.queue.ReplicationQueue">
  <Option cardinality="required" name="maxCapacity" value="200"/>
  <Option cardinality="required" name="processingCapacity" value="8"/>
</Service>

The maxCapacity=200 prevents queue overflow during burst checkin events. processingCapacity should match your threadCount setting above. After editing site.xconf, rebuild the properties with xconfmanager -p and restart Windchill.

Step 4 — Enable Replication Monitoring Add this to wt.properties to get better diagnostic output during load events:

wt.fv.replication.logLevel=VERBOSE
wt.fv.replication.monitorInterval=30000

This writes replication queue depth and transfer rate to the MethodServer log every 30 seconds, so you can verify the tuning is effective.

Step 5 — Validate NFS Performance Under Load Run this on the EU-West file server during a CAD burst to confirm NFS isn’t the bottleneck after your changes:

nfsstat -c | grep -E 'timeout|retrans'
iostat -x 2 10 | grep $(basename /mnt/wc_vault)

If you still see >1% retransmit rates, escalate to your NAS team to check for NFS server thread exhaustion on the storage appliance itself.

Expected Result: After these changes, replication should sustain 50+ concurrent CAD checkins without timeout failures. In our environment with similar load profiles we saw replication error rate drop from ~12% to <0.1% after applying equivalent tuning. Let us know how it goes.

This draft is based on general Windchill knowledge. It has not been verified against your specific version and environment. Practitioners: verify the steps and share your experience below.

3

We hit something similar on 11.1 M020. The 30-second socket timeout is indeed very aggressive when the NFS server is under heavy I/O. Try bumping wt.fv.replication.socketTimeout to at least 120000 (2 minutes) as a first step. Also check if your NFS mount options include timeo and retrans settings — if the NFS client-side timeout is shorter than Windchill’s retry window, you’ll get cascading failures. Run mount | grep nfs on the file server host and share the output.

4

Check your ReplicationAgent queue depth in site.xconf. The default wt.queue.ReplicationQueue.maxCapacity is often left at 50, which gets saturated quickly with 50+ concurrent checkins. Once the queue fills, worker threads start blocking on NFS writes while holding locks, which manifests as false timeout errors even when the underlying storage is healthy. You should also verify that wt.fv.replication.threadCount isn’t competing with your MethodServer thread pool ceiling.

5

Thanks both — useful leads. I checked the NFS mount options on the EU-West file server host and found:

naseu:/vaults/windchill on /mnt/wc_vault type nfs (rw,timeo=14,retrans=3,hard,intr)

So the NFS client timeout is only 14 * 0.1 = 1.4 seconds per retransmit, with 3 retries = ~4.2 seconds total before a hard-mount hang. That’s clearly mismatched with our 30-second socket timeout in wt.properties. Should I increase timeo on the NFS side, or lower the Windchill timeout, or both? Also, what would you recommend for the ReplicationQueue capacity value?

6

You’ll want to do both, but the NFS side is your bigger problem. With hard mount and those timeo/retrans values, once the NFS server slows down under load, the kernel RPC layer retries aggressively and can actually starve other threads. Consider switching to timeo=600,retrans=5 (60-second base timeout). Also add rsize=1048576,wsize=1048576 to maximize throughput for large CAD files. For the Windchill side, I’d also look at tuning wt.fv.replication.chunkSize — the default 1MB chunks can create a lot of small NFS write operations for big assemblies. Increasing to 4MB or 8MB can reduce NFS round-trips significantly.

kavita_erp 7

“Confirmed this resolves the NFS mount timeout errors — setting timeo=600,retrans=5,hard,intr on our vault mounts eliminated replication failures under peak CAD file checkin load.”