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On 20/04/2013 17:00, Tanstaafl wrote: |
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> Thanks for the responses so far... |
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> |
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> Another question - are there any caveats as to which filesystem to use |
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> for a mail server, for virtualized systems? Ir do the same |
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> issues/questions apply (ie, does the fact that it is virtualized not |
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> change anything)? |
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> |
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> If there are none, I'm curious what others prefer. |
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> |
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> I've been using reiserfs on my old mail server since it was first set up |
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> (over 8 years ago). I have had no issues with it whatsoever, and even |
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> had one scare with a bad UPS causing the system to experienc an unclean |
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> shutdown - but it came back up, auto fsck'd, and there was no 'apparent' |
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> data loss (this was a very long time ago, so if there had been any |
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> serious problems, I'd have known about it long go). |
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> |
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> I've been considering using XFS, but have never used it before. |
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> |
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> So, anyway, opinions are welcome... |
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Virtualization can change things, and it's not really intuitive. |
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Regardless of what optimizations you apply to the VM, and regardless of |
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what kind of virtualization is in use on the host, you are still going |
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to be bound by the disk and fs behaviour of the host. If VMWare gives |
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you a really shitty host driver, then something really shitty is going |
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to be the best you can achieve. |
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Disks aren't like eg NICs, you can't easily virtualize them and give the |
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guest exclusive access in the style of para-virtualization (I can't |
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imagine how that would even be done). |
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You also didn't mention what mail server you use - implementations vary |
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a great deal. Gut feel tells me that unless you are dealing with many |
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1000s of mails in a short period you won't really need XFS's aggressive |
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caching. But I'm happy to be proved wrong and numbers tell the truth :-) |
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I think the best you will get here is a list of combinations that are |
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unlikely to suit, and you will have to do your own extensive testing to |
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find what works best in your area. |
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FWIW, I have two mail relays (no mail storage) running old postfix |
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versions on FreeBSD. I expected throughput to differ when virtualized on |
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ESXi, but in practice I couldn't see a difference at all - maybe the |
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mail servers were very under-utilized. Considering this pair deal with |
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anything between 500,000 to a million mails a day total, I would not |
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have considered them "under-utilized". Just goes to show how opinions |
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are often worthless but numbers buys the whiskey :-) |
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-- |
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Alan McKinnon |
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alan.mckinnon@×××××.com |
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