Take the 2-minute tour ×
Server Fault is a question and answer site for system and network administrators. It's 100% free, no registration required.

I have an EBS volume specifically dedicated to storing remote backups via rsync. This volume is attached and mounted to an EC2 instance. The user mediating backups has access to this volume via a symbolic link in the user's home directory. Everything seems to be functioning fine. The user writes to a folder and the writes all go to the attached volume, making it so that I only ever need to snapshot the backup volume.

However, here's the catch: When I monitor this volume in the EC2 Management Console no writes ever appear on this volume! In fact, all the writes are logged as going to the root volume.

My question is: Is this just a problem with AWS not properly accounting for disk writes that pass through a symbolic link across volumes? Or is there perhaps something wrong with my setup that I should be concerned about?

share|improve this question

1 Answer 1

up vote 1 down vote accepted

Amazon has no visibility to how the EBS volume is being used, so it's safe to say that something in your setup is awry.

If, in the AWS Console, you're seeing writes to the root volume, then writes are happening on that volume.

You may want to try just mounting the directory in your rsync user's home directory.

share|improve this answer
    
I thought hard links only work within a single volume? –  merv May 19 '13 at 3:25
    
Yes, that's true. So why not just mount the vol directly in this user's home? –  EEAA May 19 '13 at 3:26
    
Yeah, my only reasoning in setting up was that I like to keep mounted volumes in the /mnt. But that's just convention/habit - I could change it. I'm going to investigate a little further, since as far as I can tell the writes are going to the mounted volume, despite the EC2 reports. –  merv May 19 '13 at 3:44
    
I guess the other question I have is: why can't the rsync user just access the volume where it's mounted under /mnt? –  EEAA May 19 '13 at 3:49
    
It's not that they can't write to /mnt, it's whether it's good practice. Maybe I overthink this, being primarily a developer and not a system admin, but to me it seems the remote user gains nothing by knowing the directory they back up to is on a mounted volume. In fact it only strengthens the coupling. Moreover, what if in the future I migrate the volume somewhere that has already reserved that specific mount point? Sure it's a low probability, but it's still a consideration. I also feel more comfortable knowing non-administrative users are restricted to their own home directories. –  merv May 19 '13 at 4:57

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.