Mailinglist Archive: opensuse-factory (776 mails)

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Re: [opensuse-factory] Re: BtrFS as default fs?
On 9/4/13 10:49 PM, Andrey Borzenkov wrote:
В Wed, 04 Sep 2013 12:04:58 -0400
Jeff Mahoney <jeffm@xxxxxxxx> пишет:

- VM image performance
- Performance is generally regarded as horrible.
- This is because CoW on what is essentially a block device backing
store means a ton of write amplification for each write that the
VM issues.

Why VM is special cased here? What makes it so different from any
normal write activity?

That it's significant overwrite activity with a strong desire for
snapshot functionality. The typical database workload wants /just/
overwrite. The typical VM workload wants both.

Did anyone look at what Solaris does? They must have hit the same
problem with LDOM on ZFS years ago.

Nope. We haven't examined ZFS behavior. That gets tricky WRT legality.


Jeff Mahoney

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