Binary package hint: ubiquity
I performed a reiserfs install in kvm with today's Ubuntu Hardy i386 DVD image. With a 5GiB disk image, I allocated 5000MB (note decimal units, per partman's usual behaviour) for /, allowing a few hundred MB for swap. Unlike a previous run with a smaller disk image, there was no error indicating that I had too little disk space to perform the installation (the DVD live filesystem is large so it takes more space than a desktop installation). Nevertheless, the installation failed later while copying files, with an out-of-space error.
syslog and partman are attached. The partition_too_small check runs 'du -s --block-size=1 /rofs', which returns 4540861440. 'du -s --block-size=1 /target' after the failure returns 4943574528. My guess is that reiserfs is allocating significantly more extra space over and above raw file size than ext3 does, although reiserfstune indicates that the journal size is only about 32MiB so it can't be that.
I had a similar problem installing 10.10 on an eeepc with 4g of ssd. I used 250mb for /boot, 500mb for swap and the rest for /.
The install hung halfway through with a "no space left on device" error. Surely the installer knows roughly how large the install is, and should warn if the selected partition isn't big enough?