ECS: NFS Write Throws an I/O Error after a Certain Amount of Data

Summary: NFS writes fail with an I/O error due to a synchronization mismatch.

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Symptoms

There is a new file system-enabled bucket.

NFS writes fail with an I/O error due to a synchronization mismatch.

NFS client example of the issue: 
root@client~:/mnt_ecs# dd if=/dev/zero of=/mnt_ecs/test bs=1024 count=80000
dd: write error: I/O error
dd: write error: I/O error
root@client:/mnt_ecs# ll
total 8222
drwx---rwx- 3 2147483647 2147483647 96 Aug 13 10:51 .
drwxr-xr-x- 30 root system 4096 Aug 07 10:46 ..
-rw-r--r--- 1 root system 2102272 Aug 13 10:51 test
Per the logs location below: (An expected request was not seen on the dataheadsvc service)
Command: 
# cat /opt/emc/caspian/fabric/agent/services/object/main/log/dataheadsvc.log
Example: 
admin@node1~>cat /opt/emc/caspian/fabric/agent/services/object/main/log/dataheadsvc.log
2018-08-17T06:09:02,499 [RpcDispatcherWriteIO-5411370]  INFO  RpcProgramNfs3.java (line 241) No sync response, expect an async response for request  WriteRequest : FileHandle:[objectId = e7e6d9327488f5a316420e1f8805fac18d8a4f0773173ff12de2512a384d25de, ownerZoneUUID = 4f7a7b18-4e08-4e25-9bbb-ebeb02b085c3]Export:2 offset:0 count:524288 stablehowUNSTABLE
2018-08-17T06:09:03,261 [RpcDispatcherMD-5323256] ERROR  RpcProgramNfs3.java (line 277) Error processing NfsRequest: xid:1229074411 ip:/<Client IP> SysSecurity:  AuthStatus:AUTH_OK Uid:0 Gid:0 Proc:SETATTR SetAttrRequest : FileHandle:[objectId = e7e6d9327488f5a316420e1f8805fac18d8a4f0773173ff12de2512a384d25de, ownerZoneUUID = 4f7a7b18-4e08-4e25-9bbb-ebeb02b085c3]Export:2 SetAttr3Object : uid:0 gid:0 mode:0 atime:null mtime:null verf:10487808 updateFields:[SIZE] check:true ctime(NfsTime-1534486142s, 467000000ns) NfsResponse:  SetAttr3Response : status:NFS3ERR_NOT_SYNC wccData: WccData: WccAttr: size:10485760 mtime:(NfsTime-1534486142s, 600000000ns) ctime:(NfsTime-1534486143s, 243000000ns) postOpAttr type:NFSREG mode:rw-r--r-- nlink:1 uid:0 gid:0 size:10485760 used:10485760 rdev:(Specdata3: specdata10, specdata2:0) fileid:1019241384186633961 atime:(NfsTime-1534486143s, 243000000ns) mtime:(NfsTime-1534486142s, 600000000ns) ctime:(NfsTime-1534486143s, 243000000ns) RpcError: null

Cause

There is a synchronization mismatch between client and server.
  1. Either the client mounted the file system-enabled bucket with the sync option.
 Command: (No output expected) 
# mount -V nfs -o vers=3,proto=tcp,port=2049,sync <ECS IP> :/ns_nfs/nfs /mnt_ecs
  1. The Export Host Option in the ECS UI File Menu has been changed to Sync (default is Async)
The Export Host Option in the ECS UI File Menu has been changed to Sync (default is Async)

Resolution

Run the following checks:

  • Check if the client specifies the Sync Mount option, and if so, remove it.
  • Check the Write Transfer Policy in the Export Host options (File > Exports), and change it to Async.
NFS v3 allows for safe asynchronous writes which increases performance over synchronous writes that were often a problem in earlier NFS implementations.
 
Note: Increasing the wsize in the mount option allows for more data to be transferred before the I/O error shows up.

From the RFC 1813 NFS Version 3 Protocol This hyperlink is taking you to a website outside of Dell Technologies.: 
NFS3ERR_NOT_SYNC:
Update synchronization mismatch was detected during a SETATTR operation.

Affected Products

Elastic Cloud Storage

Products

ECS Appliance, ECS Appliance Hardware Gen1 U-Series, ECS Appliance Software with Encryption, ECS Appliance Software without Encryption, Elastic Cloud Storage
Article Properties
Article Number: 000042461
Article Type: Solution
Last Modified: 03 Sep 2025
Version:  5
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