Dear Xrootd Gurus,

As you know, we are trying to evaluate xrootd to see if it does what we 
need. We have some questions that may speed along our understanding.

1. When a request is made for a file that has to be staged from an HSM 
server, we would like to get back either:
a) an estimate of how long it will be before the file is ready for 
reading, or
b) a least a bit indicating that this request will wait for staging.
Is this possible without "major" changes?  The "prepare" request looks 
like it has space for an arbitrary response, but it isn't clear to me 
from the protocol description how arbitrary it really is. It may be 
that open needs to send back an indicator as well, but that may be 

2. Is there a way to pin a file once it has been staged to a disk 
server, so that it is not a candidate for removal from the server? If 
so, is this done on a per-file basis, and/or a per-directory basis?

3. Is there anyway a file can be dropped from a disk server while a 
client has it "open"?  If so, will subsequent access attempts result in 
a new redirect or recache attempt?

4. Does xrootd automatically replicate a file to an additional server 
if demand for that file gets too high for a single server to sustain?  
All that I've read suggests that it does, but I'm having a little 
trouble tracking down the code that does the work.

Many thanks for your assistance.

Gregory J. Sharp                   email: [log in to unmask]
Wilson Synchrotron Laboratory      url:
Dryden Rd                          ph:  +1 607 255 4882
Ithaca, NY 14853                   fax: +1 607 255 8062