AFAIK, the default block size of a reiserfs is 4096 bytes. So, you can use this value unless you have specified something else when you have created the partition.
Note that you can get the block size of a reiserfs partition using the command debugreiserfs
. However, if you boot from the slackware dvd, this command is not available. To workaround this, you can proceed as below once you have booted from slackware dvd :
$ mkdir slackdvd reiserfstools
$ mount /dev/sr0 /slackdvd
$ cd reiserfstools
$ cat /slackdvd/slackware64/a/reiserfsprogs-*.txz | xz -dc | tar xf -
$ ./sbin/debugreiserfs /dev/sda3 | grep -i blocksize
If you need to get the sector size(s) of your hdd, you can use the command parted
as below :
$ parted /dev/sda print | grep -i "sector size"