Having trouble mounting an EFS to an EC2 instance

Question

I have an EFS and an EC2 instance that are both in ap-northeast-2. 
I've changed the region to ap-northeast-2. I've added the port 2049 tcp setting to both EFS and EC2 but the EFS won't mount when attempted using the attachment string auto-generated by aws: `sudo mount -t nfs4 -o nfsvers=4.1,rsize=1048576,wsize=1048576,hard,timeo=600,retrans=2,noresvport fs-xxxxxxxxxxxxxx.efs.ap-northeast-2.amazonaws.com:/ efs`. The EFS is visible when I run `aws efs describe-file-systems`.
I keep getting a timeout error message whenever I try to mount. 
Please help. Thanks!

gokul_guna · Accepted Answer

Hello,

You have mentioned that you changed the region , hope both ec2 and efs are in same region ap-northeast-2 now. Can you ensure below things ?
* Whether mount targets created for efs and the security group allowing port 2049 from ec2 security group , and vice versa that ec2 allowing port 2049 from efs security group.
* Both ec2 & efs security groups having outbound rules (default 0.0.0.0/0) 
* the directory that you are trying to mount exists (example /efs)
* Instead of DNS names of efs (fs-xxxxxxxxxxxxxx.efs.ap-northeast-2.amazonaws.com), try with ip as well.

mahankali vamseekrishna · Answer

Hi
You can go through this once;

Security groups not allowing access (TCP 2049).
Incorrect EFS file system ID in mount command.
Missing EFS utilities package (non-Amazon Linux 2).
DNS resolution problems on EC2 instance.

**Troubleshooting Steps**:
Verify security group rules for both EFS and EC2.
Double-check the EFS file system ID in your mount command.
Install amazon-efs-utils if needed.
Test DNS resolution from EC2 to EFS DNS name.
Try temporary mount with -o no_subtree_check (for diagnostics).
Confirm EC2 instance has IAM permissions for EFS access.
Review AWS CloudTrail and EC2 logs for errors.

**Additional Resources**:
EFS Mounting Guide: https://docs.aws.amazon.com/efs/latest/ug/mounting-fs.html
EFS Mount Helper: https://docs.aws.amazon.com/efs/latest/ug/efs-mount-helper.html

rePost-User-5201410 · Answer

Thank you!

Having trouble mounting an EFS to an EC2 instance

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