Re: Open RFIO file and SysErrors between UPDATE and READ

Hi Marco,

Good that you found a solution.

In principle both TRFIOFile and TCastorFile do the same thing, i.e. access the
CASTOR storage for reading or writing files.

One difference is in the remote daemon, i.e. the application that does the work to
open the file remotely and sends back / receives the data to / from the user.
TRFIOFile talks to a daemon called 'rfiod', part of the CASTOR package. TCastorFile uses the 'rootd' daemon, delivered with ROOT. During stress tests some experiments experienced some instabilities with 'rfiod', which disappeared switching to 'rootd'. Since then, the CASTOR people
run also 'rootd' on their servers.

Another difference, relevant if you are working with ROOT trees, is that 'rootd'
supports vector-buffer reading, a feature that allows to optimize the access to
trees, significantly speeding-up reading operations.

Gerri

Marco Calviani wrote:

> Hi Gerardo,
> thanks for your hints. Actually the problem is on the server side,
> but i've created a short while loop where, after a given sleep time,
> it tries to open the remote file again.
>
> Sorry what's the difference (advatages) between TRFIOFile and
> TCastorFile? Since i'm writing and reading back ROOT files from
> CASTOR?
>
> Regards,
> m
>
> On 2/12/07, Gerri Ganis <gerardo.ganis_at_cern.ch> wrote:
>
>>
>> Dear Marco,
>>
>> What you tried seems fine. Perhaps there is a problem on the server
>> side.
>> Can you create a new file there, e.g.
>>
>> TRFIOFile *f = new
>> TRFIOFile("/castor/cern.ch/user/c/calviani/DST/FIC1/dum.root", "NEW")
>>
>> ?
>>
>> Also, could you try with TCastorFile
>>
>> TFile *f =
>> TFile::Open("castor:/castor/cern.ch/user/c/calviani/DST/FIC1/data_run8207_0_s4_IDriv16.root","UPDATE")
>>
>>
>> or directly
>>
>> TFile *f =new
>> TCastorFile("/castor/cern.ch/user/c/calviani/DST/FIC1/data_run8207_0_s4_IDriv16.root","UPDATE")
>>
>>
>> ?
>> (TCastorFile is an alternative way to access CASTOR which uses different
>> daemon).
>>
>>
>> Gerri
>>
>> --
>> +--------------------------------------------------------------------------+
>>
>> Gerardo GANIS PH Department, CERN
>> address CERN, CH 1211 Geneve 23
>> room: 32-RC-017, tel / fax: +412276 76439 / 69133
>> e-mail gerardo.ganis_at_cern.ch
>> +--------------------------------------------------------------------------+
>>
>>
>>

-- 
+--------------------------------------------------------------------------+
  Gerardo GANIS    PH Department, CERN
        address    CERN, CH 1211 Geneve 23  
                   room: 32-RC-017, tel / fax: +412276 76439 / 69133
         e-mail    gerardo.ganis_at_cern.ch
+--------------------------------------------------------------------------+