On Fri, Oct 09, 2020 at 11:18:38AM -0400, Digimer wrote: > On 2020-10-09 10:43 a.m., Zdenek Kabelac wrote: > > Dne 09. 10. 20 v 15:12 Digimer napsal(a): > >> Hi all, > >> > >> I'm storing LVM information in a postgres database, and wanted to use > >> the UUID from the PVs / VGs / LVs as the UUIDs in the database. I > >> noticed when I tried to do this that postgres complained that the UUID > >> was not valid. I checked with an online UUID validator > >> (https://www.freecodeformat.com/validate-uuid-guid.php) and it also > >> reported as invalid. > >> > >> Example; > >> > >> ==== > >> # pvdisplay | grep UUID > >> PV UUID jLkli2-dEXx-5Y8n-pYlw-nCcy-9dFL-3B6jU3 > >> ==== > >> > >> Is this a known issue? > >> > > > > Hi > > > > At the time of lvm2 devel I believe UUID was just a unique identifier, > > later some effort to standardize it came in. > > > > But really you should NOT be using basically internal unique identifiers > > in your DB - this are internal to DM/LVM work and might be changed at > > any time to something else. > > > > User is supposed to use 'vgname' & 'lvname' - so there you can put those > > valid UUID sequences - although human readable strings are always nicer ;) > > > > Zdenek > > The trick is that VG and LV names can change, so I wanted to use the > (so-called) UUID as a way to keep track of a given item through name > changes. > > I suppose I'll have to rework to use the internal "UUIDs" as more like > serial numbers instead... Well, if we are stuck with non-standard "UUID"s, at least they are meant to be Universally Unique, so they can be treated as unique opaque string tokens. Or you might find a library function that can return the unencoded binary value and you can encode it as you please. However, the issue of persistence remains. FWIW I think it's quite reasonable for someone to want immutable unique identifiers for distinct objects such as LVM PVs, especially when the "unique identifier" part is already available and quite visible. -- Mark H. Wood Lead Technology Analyst University Library Indiana University - Purdue University Indianapolis 755 W. Michigan Street Indianapolis, IN 46202 317-274-0749 www.ulib.iupui.edu
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