Coda File System

Re: partitions and partition sizes

From: Ivan Popov <>
Date: Sat, 2 Apr 2005 14:02:58 +0200
Hi Patrick,

On Fri, Apr 01, 2005 at 05:31:13PM -0700, Patrick Walsh wrote:
> to tell what's still applicable and what's not (for example, the Coda
> HowTo still recommends the 4% rule of thumb).

it is still applicable for "typical Unix" files -
unless you have run rvmsizer on your data and know you have a different
rvm usage pattern.

> 	Our total storage need in coda will be around 40gb.

Then you want to run rvmsizer to check - probably you will be fine with
one server process, then use the maximal rvm size available, 1G.

> * First question: What is the optimal size of a volume?  Is it still
> true that smaller volumes are better?  The data would separate naturally
> into four different volumes of varying sizes from 2gb to 18gb.  But is
> there a benefit to doing this?

Smaller is better, as some operations are done per volume, some are
serialized per volume, so you get better performance and robustness
with multiple smaller volumes. I am using several hundred volumes
for a fraction of your expected data amount.

I always recommend to name volumes like their mountpoints,

volume "/important/data/version/1" to be mounted on
/coda/your.realm/important/data/version/1 created by
"cfs mkm /coda/your.realm/important/data/version/1"

to make volume management easy and straightforward.

Unfortunately, volume name length is limited currently to about 30 characters.

> * Second: I think I remember reading something about avoiding ext3.  Is
> that for the actual files?  Or just for rvm metadata and logs?  

It is no problem nowadays.

> * Third: Is there any rule of thumb for how large to make the rvm log
> partition(s)?

Use files instead. 1G data and several megabytes log (nobody know for sure
what is the safe lowest value possible, it depends on many things,
take 20M and you will be ok)

> * Fourth: Is it still true that partitions are superior to files?

No. There is no reason to prefer partitions to files any more.

> * Fifth: Do I want my data to be on a separate partition from the rest
> of the system?

Probably yes, to somewhat protect yourself and your data from "disk full".

> * Finally: If I use four volumes and put all of the actual data in
> a /vicepa dir on my main system partition, do I then need 8 partitions,
> 2 RVM partitions for each volume?  Or can I have one big RVM log and one
> big RVM metadata partition shared between the volumes.

The rmv data (and log) is one big chunk of data, per server process.
You do not want to use multiple server processes unless you are forced to.
You would be forced if you have too many files and 1G rvm is too little.

A "volume modification log" which you can encounter is a totally different
thing. It is allocated inside rvm, per volume.

Received on 2005-04-02 07:05:34