[Lustre-devel] Fwd: Question on path name resolution in Lustre

[vilobh meshram]

---------- Forwarded message ----------
From: vilobh meshram <meshram.vilobh at gmail.com>
Date: Thu, May 5, 2011 at 2:37 AM
Subject: Question on path name resolution in Lustre
To: lustre-discuss <lustre-discuss at lists.lustre.org>,
lusre-devel at lists.lustre.org


Hi,

I have noticed that for file or directory kind of operation in Lustre, the
Lock Manager grabs an EX (Exclusive lock) on the parent directory and then
creates a directory or file inside it.Is there a specific reason behind this
logic or implementation.

e.g. : If we want to create foo.txt in /d1/d2/d3/d4/d5/foo.txt

We grab the lock on /d1
then we grab the lock on /d1/d2
then we grab the lock on /d1/d2/d3
then we grab the lock on /d1/d2/d3/d4
then we grab the lock on /d1/d2/d3/d4/d5
then we create the file.
This is what I have seen in logs.

Is this the correct method followed during first time file access or file
creation ?

If yes then how is the performance when the directory depth is very high ?

If no can you explain me how it happens.

Thanks,
Vilobh
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