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