From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dave Hysom Date: Tue, 14 Jun 2011 16:45:59 -0700 Subject: [Lustre-devel] extremely slow reads at 1024 procs Message-ID: <4DF7F2B7.1010606@llnl.gov> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: lustre-devel@lists.lustre.org All, I've just joined to list and will be searching the archives in case this has been addressed before -- so please point me to a past thread as appropriate. Scenario: We have ~100K files. Each is 8Mb. Each is read once, by a single processor, using fread. Once we reach a certain number of processors (512 or 1024) some of the reads take enormous amounts of time, up to 15 minutes. Our files have stripe=2, which I'm told should be adequate. Our application is I/O intensive. Has anyone had similar experience, and/or have a clue what might be going on, and/or let me know what additional details I should include? thanks, David