On 13/06/11 10:28 AM, Nico Williams wrote:
On Sun, Jun 12, 2011 at 4:14 PM, Scott Lawson
<scott.law...@manukau.ac.nz> wrote:
I have an interesting question that may or may not be answerable from some
internal
ZFS semantics.
This is really standard Unix filesystem semantics.
I Understand this, just wanting to see if here is any easy way before I
trawl
through 10 million little files.. ;)
[...]
So total storage used is around ~7.5MB due to the hard linking taking place
on each store.
If hard linking capability had been turned off, this same message would have
used 1500 x 2MB =3GB
worth of storage.
My question is there any simple ways of determining the space savings on
each of the stores from the usage of hard links? [...]
But... you just did! :) It's: number of hard links * (file size +
sum(size of link names and/or directory slot size)). For sufficiently
large files (say, larger than one disk block) you could approximate
that as: number of hard links * file size. The key is the number of
hard links, which will typically vary, but for e-mails that go to all
users, well, you know the number of links then is the number of users.
Yes this number varies based on number of recipients, so could be as many a
You could write a script to do this -- just look at the size and
hard-link count of every file in the store, apply the above formula,
add up the inflated sizes, and you're done.
Looks like I will have to, just looking for a tried and tested method
before I have to create my own
one if possible. Just was looking for an easy option before I have to
sit down and
develop and test a script. I have resigned from my current job of 9
years and finish in 15 days and have
a heck of a lot of documentation and knowledge transfer I need to do
around other UNIX systems
and am running very short on time...
Nico
PS: Is it really the case that Exchange still doesn't deduplicate
e-mails? Really? It's much simpler to implement dedup in a mail
store than in a filesystem...
As a side not Exchange 2002 + Exchange 2007 do do this. But apparently
M$ decided in Exchange
2010 that they no longer wished to do this and dropped the capability.
Bizarre to say the least,
but it may come down to what they have done in the underlying store
technology changes..
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