Forwarding here for discussion. Some notable points:
1- this is about vos reporting for Demand Attached volumes (or other tools that call the UV_ListVolume RPC and its associated RPCs), not cache managers, and non-DAFS has no change 2- as noted in Ali's mail, existing/legacy vos will continue to work as-is and not return the new values, so any tools built on top of vos can either change (if they want to support the new values) or not. 3- tools or utilities that call the underlying UV_ListVolume RPC directly will receive the new values. It seems there are two basic options: 1- use the existing RPCs 2- create new RPCs Additionally, at least one person has raised a concern about exposing internal state via vos being too tight of coupling, inhibiting future work on DAFS (e.g., impacting a possible volume state redesign). I'd like suggestions as to how we propose to deal with that. Apologies to anyone whose comments I've overlooked or misrepresented. Thanks, Steven ---------- Forwarded message ---------- From: Alistair Ferguson <[email protected]> Date: Wed, Jul 22, 2009 at 3:26 AM Subject: [OpenAFS-devel] RFC: Status returned by vos for pre-attached volumes on demand-attach To: openafs-devel <[email protected]> Hi, We would like to solicit the opinion of the OpenAFS community on what status vos should return for pre-attached volumes. The demand-attach file-server introduces a number of volume states that vos is currently unable to transparently report. Instead, it simply returns on-line or off-line. The following comment details when the volume is reported as off-line: /* Conditions that offline status is based on: volume is unattached state volume state is in (one of several error states) volume not in service volume is not marked as blessed (not on hold) volume in salvage req. state volume needsSalvaged next op would set volume offline next op would not leave volume online (based on several conditions) */ otherwise, it is reported as on-line. The conditions above follow the general (mis-)perception that volumes with an off-line status are in error. The question concerns the status reported for volumes that are "pre-attached". These are volumes that the file-server hasn't fully attached because they haven't been accessed (or attached and subsequently un-attached because they haven't been accessed in a certain period of time). Currently, these volumes are reported as on-line, since they aren't in error. However, we believe that we need more informative reporting for these volumes for a number of reasons: * strictly speaking, the volumes aren't on-line * there are a number of ways to determine pre-attached volumes (dump the file-server state, fssync-debug, ...), but all need to be executed locally on the file-server * pre-attached vs attached state is interesting, since it helps determine exactly what percentage of volumes on a file-server are actually in use There are at least four options: 1. expose all underlying states to vos examine 2. expose pre-attached to vos examine 3. convert pre-attached to on-line for vos (the current behavior) 4. convert pre-attached to off-line for vos Option 3 is currently implemented and is the least desirable. Our suggestion is that we implement option 1, which will require exposing the current volume state onto the inUse field in the FillVolInfo function in the volserver. The vos command would need to be modified to be aware of the new values, but unmodified vos commands would report off-line for volumes in a state other than fully attached. Note that options 1 and 2 involve a change in behaviour for sites running demand-attach. Comments, concerns, agreement? ali _______________________________________________ OpenAFS-devel mailing list [email protected] https://lists.openafs.org/mailman/listinfo/openafs-devel _______________________________________________ AFS3-standardization mailing list [email protected] http://michigan-openafs-lists.central.org/mailman/listinfo/afs3-standardization
