Re: How to format RAID1 correctly

[Helmut Tessarek <tessarek@evermeet.cx>]

On 2014-09-24 0:09, Stan Hoeppner wrote:
> If you create any striped arrays, especially parity arrays, with md make
> sure to manually specify chunk size and match it to your workload.  The
> current default is 512KB.  This is too large for a great many workloads,
> specifically those that are metadata heavy or manipulate many small
> files.  512KB wastes space and with parity arrays causes RMW, hammering
> throughput and increasing latency.

Thanks again for the valueable information.

I used to work with databases on storage subsystems, so placing GBs of
database containers for tableapaces on arrays with a larger stripe size
was actually beneficial.
For log files and other data I usually used different cache settings and
strip sizes.

So how does this work with SW RAID?

Does the XFS chunk size equal the amount of data touched by a single r/w
operation?
I'm asking because data is usually written in page/extent sizes for
databases. Even if I have a container with 50GB, I might only have to
read/write a 4k page.

Cheers,
 K. C.

-- 
regards Helmut K. C. Tessarek
lookup http://sks.pkqs.net for KeyID 0xC11F128D

/*
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