[OpenAFS] OpenAFS in the ISP environment. A good idea...

[Leland J. Steinke]

Derrick J Brashear wrote:
> On Thu, 6 Mar 2003, Leland J. Steinke wrote:
> 
>>2)  How many volumes can we reasonably expect to fit in a single cell?  Earlier 
>>discussions mentioned 40K, 60K, and 100K+ volumes per cell;  we would be looking 
>>at few, if any, backup volumes and most volumes will be read/write.  A related 
>>question is how many volumes can fit on a single disk partition before things 
>>start to break?  archov-doc.pdf mentions a maximum of 3500, but that document is 
>>over ten years old.
> 
> 
> How much data will the volumes have, how big are the partitions, and how
> much overcommitting do you want to do?
> 
> Lease space for the backup volume clones (a complete turnover could cause
> a 100% greater disk usage if the quota was used up and then entirely
> turned over the contents, but that's not worth worrying about)

Here is the hard part.  Essentially, our customers have a 100M quota.  The 
average mailbox size is <1M.  If I add in the average usage for personal 
webspace, it comes to just 1M/user average.  I would not want to do a 100-to-1 
oversell, but I think 25 or 50 to 1 would not be inappropriate.

I was wondering if the 3500 cell/partition was a software limit.  Your reply 
seems to indicate that it is more of a "how many do you want fit in the 
partition" issue.  I will put this another way:

Assume 100K user volumes, each with 100M quota, and a 50-to-1 overcommit, so the 
total storage requirement is 200G (this is way in the future).   Assume further 
that there are two servers (initially) in the AFS cell, each with 100G of RAID5 
available for AFS.  Could I do a single partition per machine with 50K volumes 
on each, or should I put more partitions on the RAID array to get the number of 
volumes/partition down to the 3-5K range?  When does the number of volumes per 
partition become problematic.  Is it a function (as you imply above) of 
partition size, volume size (and distribution thereof), and number of volumes in 
the partition?

If there is a link describing how to design a cell to support X number of 
volumes of average size Y across Z number of servers with W load, it would be 
very helpful.

> 
> 
>>3)  What is the status and future of OpenAFS, if my reading of IBM's 
>>discontinuation of support for AFS is correct?  Is AFS a technology just waiting 
>>to explode across the Internet (I saw Avi Freedman's endorsement of AFS over NFS 
>>in the premier issue of ACM Queue this month.) or is it a niche technology 
>>looking for the right time to die?
> 
> 
> You're asking in the wrong place. Rosy glasses and such.

I figured as much, but it does not hurt to ask.  ;-)


Leland