Posted: Tue Jun 09, 2009 3:55 pm Post subject: Examining Additional Volumes
I'm curious, thought I'd ask the boffins here - when you're running an installer such as one of NeoOffice's patch installers, at a certain point the installer says: Examining Additional Volumes... sometime it does that quickly, and sometimes it seems to take up to 20 seconds, even when there's only one mounted volume (apart from the one with the installer in it).
Any ideas why it might take so long sometimes? I wonder if it's connected with the number of dmg files that have been mounted since the last login - perhaps there's a database of previously mounted volumes that the installer has to go through to see if any of them are currently mounted or something? Otherwise it just seems really random.
Joined: May 25, 2003 Posts: 4752 Location: Santa Barbara, CA
Posted: Tue Jun 09, 2009 9:45 pm Post subject:
Hmm, I don't know why it would take more time related to mounted .dmgs, but the more volumes it definitely will take more time. A lot of it depends on how the person who wrote the installer wrote the "VolumeCheck" script. Older Installer.app versions used to do this across disks serially, IIRC, but I think starting with Installer.app 2.0 it's now done in parallel across all disks at the same time. I may be totally wrong on that change since I haven't tried 10.3 in a while
The problem is if you're doing something like searching for specific files on a hard drive with find, depending on the computer it may actually be slower todo it in parallel than serially (e.g. more collisions on a single FireWire bus, more time waiting for drive I/O). Plus, if the search location isn't restricted, larger hard drives tend to have more files and just take longer to search.
It will try to run for mounted disk images too, but if they're unmounted in theory no additional overhead should be encountered.
Not even sure if that's correct, but that's my first guess as to why things now seem to take longer with multiple volumes than they did a long time ago
Aye, but this behaviour I'm describing happens when there's only two mounted volumes - the startup volume, and the installer app's mounted dmg volume. No firewire or usb drives active, only a few unmounted dmgs knocking around in the Downloads folder or on the desktop.
Sometimes it's more or less instantaneous, sometimes it takes up to 20 seconds or more. And that applies to, for example, iterations of the NeoOffice patch installer, so it varies even with the same installer app compiled by the same devs.
Oh well, a mystery. Probably under Snow Leopard it'll do it before I even launch the installer .
You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum You cannot attach files in this forum You cannot download files in this forum
. I'm practising my Australian-American accent even as we 'speak'...