[sheepdog-users] Sheepdog 0.80: Queries and feedback

[Hitoshi Mitake]

Hi Struan,

This is Hitoshi. Thanks for your feedback and sorry for my late
reply. I'm a little bit busy with ongoing GC algorithm update and
other work.

Fortunately, other community participants are joining to the
discussion and giving answers to your questions. But as you say, some
docs would be obsolete and should be fixed. Could you add issues to
our bug tracker? :
https://launchpad.net/sheepdog-project

Mailing list is a good place for discussion but not suitable for
storing issues.

Thanks,
Hitoshi

At Wed, 12 Mar 2014 20:05:32 +0000,
Struan Bartlett wrote:
> 
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> Hi
> 
> Having been trialling sheepdog for a number of days now. It's a really 
> good concept, and has moved on a lot since the last time I tried it 
> (around 0.40 version). After a fair few hiccups getting it properly set 
> up and working, version 0.80 is working reasonably well. I'd like to 
> offer some initial feedback on some of the challenges I faced:
> 
> 1. The README says you need a minimum of 3 nodes, which must be x86_64. 
> Sheepdog compiles for i386, and it appears possible to format a cluster 
> with 'dog cluster format -c 2' and I seem to have been able to run a 
> cluster with two copies, on i386, quite stably. Is this line in the 
> README just out of date? If so this is misleading and it would be 
> helpful to correct it.
> 
> 2. Having formatted a cluster with 'dog cluster format' I am not aware 
> of a way to determine the format options used (e.g. number of copies). 
> It would be helpful if e.g. 'dog cluster info' would display this 
> information.
> 
> 3. I couldn't find documentation of the existence/functionality of the 
> sheep gateway option anywhere on 
> https://github.com/sheepdog/sheepdog/wiki or 
> http://www.sheepdog-project.org/doc/. Maybe I missed it (though I have 
> grepped the former and searched the latter). This is such a useful 
> option, that it does sheepdog a disservice that it's not highlighted 
> better. The manpage only says '-g make the progam run as a gateway mode' 
> which doesn't explain what gateway mode is. In the end, I found out by 
> emailing this list. It would be helpful to have this option better and 
> more widely documented.
> 
> 4. The manual/help says that 'dog vdi check <vdi>' must not be performed 
> on an actively used vdi, presumably because if it has to repair the vdi 
> it could cause corruption. If that's the case, it might be helpful if it 
> prompted the user and gave a warning before beginning. It might also be 
> helpful if 'check' were renamed 'repair' (to avoid the ambiguity). I'd 
> also suggest a pure 'check' option, that does not repair. This would all 
> be more akin to what an fsck user would expect. The same comments go for 
> 'dog cluster check' too.
> 
> 5. The manual/help says in bold letters: "Remember: DO NOT shut down any 
> of node before deactivating the cluster! DO NOT shut down / kill a node 
> after the other.". Yet isn't the point of sheepdog to be a distributed 
> highly available storage system, and isn't it intended to withstand 
> individual nodes going down, or crashing, or being shut down by errant 
> sysadmins? If so, then I'm finding this warning misleading and 
> off-putting. Unless I misunderstand, sheepdog *should* be resilient to 
> rebooting of a limited number of nodes, depending on the total number of 
> nodes, and the number of copies, shouldn't it? It would be helpful to 
> clarify this as there may be times one needs to shut down the cluster 
> safely, after a limited number of nodes have already crashed (and the 
> data in the cluster is therefore still valid).
> 
> That's my initial feedback. If I can reproduce the setup hiccups I had 
> on the latest version of sheepdog, I'll submit reports about that 
> separately.
> 
> Kind regards
> 
> Struan
> 
> -- 
> 
> Struan Bartlett
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