[CentOS] new "large" fileserver config questions

Keith Keller kkeller at wombat.san-francisco.ca.us
Wed Oct 3 14:01:40 EDT 2012


On 2012-10-03, Rafa Griman <rafagriman at gmail.com> wrote:
>
> If it works with you ... I mean, there's no perfect partition scheme
> (IMHO), depends greatly on what you do, your budget, workflow, file
> size, ... So if you're happy with this, go ahead. Just some advice:
> test a couple of different options first just in case ;)

Well, given the warnings about SSD endurance, I didn't want to do
excessive testing and contribute to faster wear.  But I've been reading
around, and perhaps I'm just overreacting.  For example:

http://www.storagesearch.com/ssdmyths-endurance.html

This article talks about RAID1 potentially being better for increasing
SSD lifetime, despite the full write that mdadm will want to do.

So.  For now, let's just pretend that these disks are not SSDs, but
regular magnetic disks.  Do people have preferences for either of the
methods for creating a bootable RAID1 I mentioned in my OP?  I like the
idea of using a partitionable RAID, but the instructions seem
cumbersome.  The anaconda method is straightforward, but simply creates
RAID1 partitions, AFAICT, which is fine till a disk needs to be replaced,
then gets slightly annoying.

> Yup, even though you've got the sw and su options in case you want to
> play around ... With XFS, you shouldn't have to use su and sw ... in
> fact you shouldn't have to use many options since it tries to
> autodetect and use the best options. Check the XFS FAQ.

Well, I'm also on the XFS list, and there are varying opinions on this.
>From what I can tell most XFS experts suggest just as you do--don't
second-guess mkfs.xfs, and let it do what it thinks is best.  That's
certainly what I've done in the past.  But there's a vocal group of
posters who think this is incredibly foolish, and strongly suggest
determing these numbers on your own.  If there were a straightforward
way to do this with standard CentOS tools (well, plus tw_cli if needed)
then I could try both methods and see which worked better.  John Doe
suggested a guideline which I may try out.  But my gut instinct is that
I shouldn't try to second-guess mkfs.xfs.

> Nope, just mass extinction of the Human Race. Nothing to worry about.

So, it's a win-win?  ;-)

--keith

-- 
kkeller at wombat.san-francisco.ca.us




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