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On Tuesday, July 01, 2014 9:44 PM, Anne Gentle <anne at openstack.org> wrote:

Thank you for the quick response.

> The install guide only recommends a single path, not many options, to ensure success.

I understand the point for writing the document.

> There's a little bit of discussion in the developer docs:
> http://docs.openstack.org/developer/swift/deployment_guide.html#filesystem-considerations
> I think that packstack gives the option of using xfs or ext4, so there must be sufficient testing for ext4.

Thank you for this info.
In the discussion, there is a following sentence.
 " After thorough testing with our use cases and hardware configurations, XFS was the best 
all-around choice."

I would like to know what kind of testing should I do from filesystem point of view?

Backgroup of this question is:
I read the following performance comparison about ext4 and xfs. There are some results of 
Benchmark. It seems that performance of ext4 is better than xfs (Eric Whitney's FFSB testing).
So I think if performance of swift is more important rather than scalability of it, it is a
good idea to use ext4.

http://www.linuxtag.org/2013/fileadmin/www.linuxtag.org/slides/Heinz_Mauelshagen_-_Which_filesystem_should_I_use_.e204.pdf

Best Regards,
Hisashi Osanai

From: Anne Gentle [mailto:anne at openstack.org] 
Sent: Tuesday, July 01, 2014 9:44 PM
To: OpenStack Development Mailing List (not for usage questions)
Subject: Re: [openstack-dev] Swift: reason for using xfs on devices


On Tue, Jul 1, 2014 at 6:21 AM, Osanai, Hisashi <osanai.hisashi at jp.fujitsu.com> wrote:

Hi,

In the following document, there is a setup up procedure for storage and
it seems that swift recommends to use xfs.

http://docs.openstack.org/icehouse/install-guide/install/yum/content/installing-and-configuring-storage-nodes.html
===
2. For each device on the node that you want to use for storage, set up the
XFS volume (/dev/sdb is used as an example). Use a single partition per drive.
For example, in a server with 12 disks you may use one or two disks for the
 operating system which should not be touched in this step. The other 10 or 11
disks should be partitioned with a single partition, then formatted in XFS.
===

I would like to know the reason why swift recommends xfs rather than ext4?

The install guide only recommends a single path, not many options, to ensure success.

There's a little bit of discussion in the developer docs:
http://docs.openstack.org/developer/swift/deployment_guide.html#filesystem-considerations

I think that packstack gives the option of using xfs or ext4, so there must be sufficient testing for ext4. 

Anne
 

I think ext4 has reasonable performance and can support 1EiB from design point of view.
# The max file system size of ext4 is not enough???

Thanks in advance,
Hisashi Osanai


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