On Tue, 2019-09-24 at 11:32 -0700, Brian C. Lane wrote: > On Thu, Sep 19, 2019 at 08:10:21PM +0800, Kalpa Welivitigoda wrote: > > Hi all, > > > > Given a kickstart file (flatten) and we intend to make an iso using > > it, is there a tool or service by which we can estimate the size of > > the final iso (based on the packages defined in the kickstart file) > > before actually creating the iso? > > AFAIK we don't have any stand-alone tools to do that, which is probably > a good thing since trying to estimate the installed size usually ends up > being very much not exact. In lorax-composer I have this: > > https://github.com/weldr/lorax/blob/master/src/pylorax/api/projects.py#L288 > > which does the raw estimation. But then there is this: > > https://github.com/weldr/lorax/blob/master/src/pylorax/api/compose.py#L738 > > Which adds 20% > > But wait, that's not all! Anaconda then adds more: > > https://github.com/rhinstaller/anaconda/blob/master/pyanaconda/payload/dnfpayload.py#L879 > > The reason behind all of this fudging is that we really don't know the > exact sizes of the installed packages, and it can be influenced by block > size, filesystem type, etc. Exactly, just for fun I'll try to enumerate the factors I can remember: - even an empty filesystem has to store it's metadata inside itself, so there will always be less useable space on a filesystem than it's raw size, this value depends on the filesystem and possibly other factors - some older/simpler filesystems (such as FAT32) are very inefficient at storing many small files which can further increase actual needed ammount of storage space - while RPMs do contain unpacked size of all the files inside, it does not list size per file, so if you have a separate mountpoint for say var, you can't know how much data will be installed in the given location by a RPM (but this is likely not a problem for image size) - RPMs can do arbitrary stuff in their scriptlets, including cache generation, that can take an arbitrary ammount o space that simply can't be estimated beforehand - when configuring the system Anaconda writes out config files, enables services and similar, which also uses up some space, though very very minor amount - kickstart describing the installation and installaiton logs are stored on the system by default, those could eat up some more space - a couple MB - AFAIK images generally use squashfs, so the content of its filesystem will be compressed, reducing it size, but again in a hard to tell beforehadn manner, based on how well the filesystem content compresses with the given algorithm used
So there is indeed quite a few variables, many with values uknown until things are already in place, which is why the various percentual & absolute size adjustments are done. Technically, I guess it might be possible to just run the size estimation code for a kickstart file and then just output the estimated number instead of starting an installation/image generation if someone finds that useful & wirtes the needed patches. :) > > Even with all this added extra space I have occasionally seen it run out > of space (usually when trying to do a smaller install than a bigger one, > where the room for error is smaller). > > The 'best' way to do what you want is to put together your kickstart, > give it a big / partition, do a build and see how much free space there > is, and trim it down. But not too far :) Definitely, this is the only real way to get real numbers with the way our seoftware & its installation process is built. Actually, I would suggest this to a regular thing, done automatically say nightly, with the results being measured & notification being sent when when a given size threashold is reached. AFAIK nothing like this is done currently and we basically only catch any signifficant size increases once they break things, which is kinda late & makes fixing things harder. > > Brian > > -- > Brian C. Lane (PST8PDT) - weldr.io - lorax - parted - pykickstart > _______________________________________________ > devel mailing list -- devel@lists.fedoraproject.org > To unsubscribe send an email to devel-le...@lists.fedoraproject.org > Fedora Code of Conduct: > https://docs.fedoraproject.org/en-US/project/code-of-conduct/ > List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines > List Archives: > https://lists.fedoraproject.org/archives/list/devel@lists.fedoraproject.org _______________________________________________ devel mailing list -- devel@lists.fedoraproject.org To unsubscribe send an email to devel-le...@lists.fedoraproject.org Fedora Code of Conduct: https://docs.fedoraproject.org/en-US/project/code-of-conduct/ List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines List Archives: https://lists.fedoraproject.org/archives/list/devel@lists.fedoraproject.org
