I'm running mongodb on some linode servers. Part of their platform allows for resizing of discs and backups, but I have to be on ext3.
Mongodb is giving me some headaches when it tries to allocated it's 2GB collection files and can block for ~40 seconds. This blocking then causes my already overloaded server to queue up and then finally just kills the web server.
Mongodb suggested using ext4 so that it can pre-allocate empty files pretty much instantly.
My real question then is, if I simply mount the existing ext3 disk as ext4 by just editing /etc/fstab will mongodb be able to use that part of ext4 (Persistent preallocation)
I've seen things like this: https://wiki.archlinux.org/index.php/Ext4#Mounting_ext3_Partitions_as_ext4_Without_Converting
that say I'll be able to use multi-block allocation and delayed allocation but I'm not sure about persistent preallocation?
Phew.
