Re: [MonetDB-users] Version 5 crashing.

Ok. I spoke to several people at Lustre and they say mmap() is implemented properly on Lustre and any application that uses mmap() should work. Is there a way to simulate a mmap() call (I am not an expert programmer). I would like to see if this is a legemit bug on MonetDB or Lustre. Would anyone like to help me with this? TIA On Wed, May 13, 2009 at 8:59 AM, Peter Boncz wrote:

I have never heard of Lustre and I am not aware of anyone using that with MonetDB.. A few years ago MonetDB still worked with (nfs) mmapped filed, but it was slow and their were consistency risks as dirtypages are not synced immediate over the network. For these reasons nobody used it. Then, it stopped working. We should clean up the crash and just make it fail or warn gracefully.

MonetDB does pretty scary stuff with mmap so without studying Lustre I cannot say wheter it could work.

On May 13, 2009, at 2:32 PM, "Mag Gam" wrote:

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Thanks for the response Peter. This is on the Lustre filesystem. http://arch.lustre.org/images/9/95/Mmap_hld.pdf

I believe it supports it without any issues. Or could this be an issue?

On Wed, May 13, 2009 at 8:29 AM, Peter Boncz wrote:

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Databases on NFS are not supported and lead to crashes on a mmaped dbfarm afaik.

On May 13, 2009, at 2:13 PM, "Mag Gam" wrote:

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Yes, have to be on a network filesystem. Its pretty fast, I can get close to 500MB/sec consistently.  Also, it has over 50TB of stable available :-)

This issue is getting very frustrating. :-(

On Wed, May 13, 2009 at 7:49 AM, Fabian Groffen wrote:

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On 13-05-2009 04:34:04 -0700, Mag Gam wrote:

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More information about the server:

MonetDB server v5.10.4 (64-bit), based on kernel v1.28.4 (64-bit oids) Copyright (c) 1993-July 2008 CWI Copyright (c) August 2008-2009 MonetDB B.V., all rights reserved Visit http://monetdb.cwi.nl/ for further information

Libraries:   libpcre: 6.6 06-Feb-2006 (compiled with 6.6)   openssl: OpenSSL 0.9.8b 04 May 2006 (compiled with OpenSSL 0.9.8b 04 May 2006)   libxml2: 2.6.26 (compiled with 2.6.26)

Compilation: gcc -O2 -std=c99 Linking    : ld -IPA -m elf_x86_64

Also,

${prefix}/var/MonetDB5/dbfarm exists on a network filesystem. I am hoping thats ok (with flocking)

Ohhh...  Never tested, but that may be (a lot) slower...  Do you really have to be on a network share?  For speed it is regardless a good idea to have the storage local.  mmapping on network shares might also be a bit less optimal.

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