On Sat, Feb 28, 2009 at 09:45:12PM -0600, Mike Gerdts wrote: > On Sat, Feb 28, 2009 at 8:34 PM, Nicolas Williams > > Right, but normally each head in a cluster will have only one pool > > imported. > > Not necessarily. Suppose I have a group of servers with a bunch of > zones. Each zone represents a service group that needs to > independently fail over between servers. In that case, I may have a > zpool per zone. It seems this is how it is done in the real world.[1]
That model forces you to allocate storage. If you're willing to take the pain of managine storage at a higher level of granularity then you're welcome to it. As has just been posted (and as anyone who read Matt Ahrens' blog entry on "block pointer rewrite" could have read between the lines), pool shrinking is coming. But I still don't recommend it. > > The Sun Storage 7xxx do this. One pool per-head, two pools altogether > > in a cluster. > > Makes sense for your use case. If you are looking at a zpool per > zone, it is likely a zpool created on a LUN provided by a Sun Storage > 7xxx that is presented to multiple hosts. That is, ZFS on top of ZFS. Running ZFS on an LUN backed by a ZFS zvol is fine. That does not force you to manage storage at the physical partition/cylinder/chunk-of- sectors level. > > This gets you back into managing physical space allocation. Do you > > really want that? If you're using zvols you can do "array based copies" > > of you zvols. If you're using filesystems then you should just use > > normal backup tools. > > There are times when you have no real choice. If a regulation or a > lawyer's interpretation of a regulation says that you need to have > physically separate components, you need to have physically separate > components. If your disaster recovery requirements mean that you need > to have a copy of data at a different site and array based copies have > historically been used - it is unlikely that "while true ; do zfs send > | ssh | zfs receive" will be adapted in the first round of > implementation. Given this, zvols don't do it today. Physically separate components accessed by a single node are not likely to meet such a regulation -- either that or the lawyers need technology training. Chinese wall requirements might need to be met by physically separate storage heads, with physically separate networks. Except that no one builds networks like that any more, at least not in the corporat world -- it's all switches and VLANs, so there will be some degree of logical separation, and the question really is: to what degree? Nico -- _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
