Re: #6173: Same volume-id on all F22 ISOs
by Fedora Release Engineering
#6173: Same volume-id on all F22 ISOs
Reporter: zeenix | Owner: rel-eng@…
Type: defect | Status: new
Milestone: | Component: koji
Resolution: | Keywords:
Blocked By: | Blocking:
Comment (by chrismurphy):
I trust that this is not easily fixed and that there are higher
priorities. But that argument is not at all related to the
appropriateness, and conformance aspect, of intentionally using the same
Volume Identifier for two obviously very different volumes.
The ISO 9660 spec makes it really clear that the Volume Identifier is
expected to be reasonably unique specifically for the purpose of volume
differentiation and therefore file location. The Volume Set Identifier can
be the same among volumes. Setting the Volume Identifier field to the same
value for two different volumes thwarts the entire purpose of the Primary
Volume Descriptor. I agree with zeenix that the current behavior is
flawed, but further I think it arguably makes these ISOs not in
conformance with ISO 9660's intent to enable the user to identify and
differentiate what are in fact different volumes.
If it's OK to do this with two ISOs, then why not do it to all ISOs and
just stick "fedora" as the Volume Identifier?
/dev/loop1: UUID="2016-06-14-15-55-58-00" LABEL="Fedora-S-dvd-x86_64-24"
TYPE="iso9660" PTUUID="041a2601" PTTYPE="dos"
Volume Creation Date and Time=2016061415555800
ISO MD5SUM = 81ffacb48528f35651fe01eaa892060d
By filename, this is the net installer, not the dvd, but the Volume
Identifier and therefore the LABEL provided by libblkid says it is the
/dev/loop0: UUID="2016-06-14-16-21-47-00" LABEL="Fedora-S-dvd-x86_64-24"
TYPE="iso9660" PTUUID="26760f17" PTTYPE="dos"
Volume Creation Date and Time=2016061416214700
ISO MD5SUM = 9e37b58618c7f598417c620f92de9d15
The ISO MD5SUMs are different because they two ISOs contain completely
different contents, and of course are intended for different installation
use cases. So saying these two volumes are sufficiently similar to give
them the same name is not compelling.
ISO 9660 has no field for UUID. It looks like libblkid is producing a UUID
based on the Volume Creation Date and Time field in the Primary Volume
Descriptor, which while it supports 1/100s precision is only populated
with 1s precision. It might be sufficiently unique anyway, but there is
also the MD5SUM field. So there are a couple of less obvious ways to know
that two identically named volumes are in fact not identical. But both
suffer from the same problem is differentiation on file size, which is
that these values aren't known until the ISO is already created.
Ticket URL: <https://fedorahosted.org/rel-eng/ticket/6173#comment:16>
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