>> It looks like there are comprehensive ZFS Gentoo docs >> (http://wiki.gentoo.org/wiki/ZFS) but can anyone tell me from the real >> world about how much extra difficulty/complexity is added to >> installation and ongoing administration when choosing ZFS over ext4? > > Very very minimal. So minimal, in fact, that if you don't plan to use > ZFS as a root filesystem, it's laughably simple. You don't even have > to edit /etc/fstab
I do plan to use it as the root filesystem but it sounds like I shouldn't worry about extra headaches. >> Performance doesn't seem to be one of ZFS's strong points. Is it >> considered suitable for a high-performance server? >> >> http://www.phoronix.com/scan.php?page=news_item&px=MTM1NTA > > Go directly to this post: > http://phoronix.com/forums/showthread.php?79922-Benchmarks-Of-The-New-ZFS-On-Linux-EXT4-Wins&p=326838#post326838 > > Notice how ZFS won against ext4 in 8 scenarios out of 9. (The only > scenario where ZFS lost is in the single-client RAID-1 scenario) Very encouraging. I'll let that assuage my performance concerns. >> Besides performance, are there any drawbacks to ZFS compared to ext4? > > 1. You need a huge amount of RAM to let ZFS do its magic. But RAM is > cheap nowadays. Data... possibly priceless. Is this a requirement for deduplication, or for ZFS in general? How can you determine how much RAM you'll need? > 2. Be careful when using ZFS on a server on which processes rapidly > spawn and terminate. ZFS doesn't like memory fragmentation. I don't think I have that sort of scenario on my server. Is there a way to check for memory fragmentation to be sure? > For point #2, I can give you a real-life example: > > My mail server, for some reasons, choke if too many TLS errors happen. > So, I placed "Perdition" in to capture all POP3 connections and > 'un-TLS' them. Perdition spawns a new process for *every* connection. > My mail server has 2000 users, I regularly see more than 100 Perdition > child processes. Many very ephemeral (i.e., existing for less than 5 > seconds). The RAM is undoubtedly *extremely* fragmented. ZFS cries > murder when it cannot allocate a contiguous SLAB of memory to increase > its ARC Cache. Did you have to switch to a different filesystem on that server? - Grant
