Re: Recovering badly closed file?

From: Brett Viren <bv_at_bnl.gov>
Date: Thu, 21 Jan 2010 14:27:50 -0500

Hi again,

Brett Viren <bv_at_bnl.gov> writes:

> Using the same versions as was used to produce the file lets me
> to a TTree::Scan() and it looks like the majority of the data is
> recoverable!

Sorry, I spoke too soon.

While I can recover the file "live" just after I open it when using the same code versions, I can not "save" this recovery by opening the file with "UPDATE" as indicated by TFile::Recover() documentation. Also, if I do an explicit call to Recover() on the file after it is opened with "UPDATE" I can not access the contents even in the immediate session.

If worse comes to worse, I can write code to manually copy the contents into a new file but maybe there is a way this should "just work"?

The following four sessions show the cases for with and without using the "UPDATE" option and with and without an implicit call to Recover().

Implicit Recover(), no UPDATE works, but file is unmodified:

---

shell> loon

loon [0] TFile* f = new TFile("B100112_080001.mbeam.tofix.root")     
loon [1] TTree* t = (TTree*)f->FindObjectAny("BeamMon")     
loon [2] t->Scan()

...

---

Explicit Recover(), no UPDATE works, but file is unmodified:

---

shell> loon
loon [0] TFile* f = new TFile("B100112_080001.mbeam.tofix.root") loon [1] f->Recover()
Info in <TFile::Recover>: B100112_080001.mbeam.tofix.root, recovered key TTree:BeamMon at address 167327993 (Int_t)(1)
loon [2] TTree* t = (TTree*)f->FindObjectAny("BeamMon") loon [3] t->Scan()
...

---

Implicit Recover, with UPDATE works, but file is unmodified:

---

shell> loon
loon [0] TFile* f = new TFile("B100112_080001.mbeam.tofix.root","UPDATE") Warning in <TFile::Init>: file B100112_080001.mbeam.tofix.root probably not closed, cannot read free segments loon [1] TTree* t = (TTree*)f->FindObjectAny("BeamMon") loon [2] t->Scan()
...
loon [3] f->Close()
loon [4] delete f

shell> md5sum B100112_080001.mbeam.{original,tofix}.root 27ea3c7e18d287eaaec13bd2357a924d B100112_080001.mbeam.original.root 27ea3c7e18d287eaaec13bd2357a924d B100112_080001.mbeam.tofix.root

---

Explicit Recover with UPDATE will update the file but the file becomes usable both immediately and if saved and (re)opened in a new session.

---

shell> loon
loon [0] TFile* f = new TFile("B100112_080001.mbeam.tofix.root","UPDATE") Warning in <TFile::Init>: file B100112_080001.mbeam.tofix.root probably not closed, cannot read free segments loon [1] f->Recover()
Info in <TFile::Recover>: B100112_080001.mbeam.tofix.root, recovered key TTree:BeamMon at address 167327993 (Int_t)(1)
loon [2] TTree* t = (TTree*)f->FindObjectAny("BeamMon") R__unzip: error in header
loon [3] t->Scan()
Error: illegal pointer to class object t 0x0 326 (tmpfile):1: *** Interpreter error recovered ***
loon [4] f->Close()
loon [5] delete f

shell> md5sum B100112_080001.mbeam.{original,tofix}.root 27ea3c7e18d287eaaec13bd2357a924d B100112_080001.mbeam.original.root bbf601f6855c0f845b9fb36dd9fa3e08 B100112_080001.mbeam.tofix.root

shell> loon
loon [0] TFile* f = new TFile("B100112_080001.mbeam.tofix.root") loon [1] TTree* t = (TTree*)f->FindObjectAny("BeamMon") R__unzip: error in header
loon [2] t->Scan()
Error: illegal pointer to class object t 0x0 326 (tmpfile):1:

---

-Brett. Received on Thu Jan 21 2010 - 20:27:58 CET