From: <lup...@vi...> - 2003-11-25 13:20:49
|
Jeff, Nuno, thanks a lot for your interest, I'm pretty sure I was not clear in my explanation ... it's my fault. I made the following attempt, based on my little knowledge of the subject= : on my host machine I have two UML root filesytems /somewhere/root-rs1 --> UML host 1, kernel with opengfs / ogfs utilitie= s /somewhere/root-rs2 --> UML host 2, kernel with opengfs / ogfs utilitie= s and a file created to mimic the shared storage /somewhere/shared_disk-1 (256 Mb) , 3 partitions (journals, data) at boot time, the above mentioned is: connected to ubd/disc[123] on UML host 1 (memexp lock server) connected to ubd/disc[123] on UML host 2 then, after (successfully) initialized ogfs filesystem, I tried mount -t ogfs -o hostdata=3DUML_host_IP_address /dev/ubd/disc1/part3 /sha= red on both "machines", just like shared_disk-1 was a SCSI disk-array, shared= between the two. Result: I had luck only on one host at a time. I guess that the first UML host to mount the udb device locks it up, prev= enting ogfs locking mechanism to take effect .. If you have any suggestion / better practice I would appreciate it Thanks Marco |
From: roland <for...@gm...> - 2003-11-25 17:48:57
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hey, i have a similar thing in mind. our dba`s want evaluate oracle RAC and i need to setup shared storage for them see: http://otn.oracle.com/oramag/webcolumns/2002/opinion/coekaerts_linux01.html this setup needs 2 PCs and 1 external Firewire HDD. I wonder, if we could do this with uml. first i need to know, if it would be generally possible , that a file can be shared as a block device between uml`s (yes - i`m aware of nbd or enbd) - but i`d like to do it without "third party kernel magic". this should avoid processing overhead and configuration hassle. if "shared-storage-file" would work, one could try to patch a uml-patched kernel with ocfs. comments? regards roland ----- Original Message ----- From: <lup...@vi...> To: <use...@li...> Sent: Tuesday, November 25, 2003 2:20 PM Subject: [uml-user] Virtual shared resource Jeff, Nuno, thanks a lot for your interest, I'm pretty sure I was not clear in my explanation ... it's my fault. I made the following attempt, based on my little knowledge of the subject: on my host machine I have two UML root filesytems /somewhere/root-rs1 --> UML host 1, kernel with opengfs / ogfs utilities /somewhere/root-rs2 --> UML host 2, kernel with opengfs / ogfs utilities and a file created to mimic the shared storage /somewhere/shared_disk-1 (256 Mb) , 3 partitions (journals, data) at boot time, the above mentioned is: connected to ubd/disc[123] on UML host 1 (memexp lock server) connected to ubd/disc[123] on UML host 2 then, after (successfully) initialized ogfs filesystem, I tried mount -t ogfs -o hostdata=UML_host_IP_address /dev/ubd/disc1/part3 /shared on both "machines", just like shared_disk-1 was a SCSI disk-array, shared between the two. Result: I had luck only on one host at a time. I guess that the first UML host to mount the udb device locks it up, preventing ogfs locking mechanism to take effect .. If you have any suggestion / better practice I would appreciate it Thanks Marco ------------------------------------------------------- This SF.net email is sponsored by: SF.net Giveback Program. Does SourceForge.net help you be more productive? Does it help you create better code? SHARE THE LOVE, and help us help YOU! Click Here: http://sourceforge.net/donate/ _______________________________________________ User-mode-linux-user mailing list Use...@li... https://lists.sourceforge.net/lists/listinfo/user-mode-linux-user |
From: Nuno S. <nun...@vg...> - 2003-11-27 06:15:01
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Hi! lup...@vi... wrote: > > I guess that the first UML host to mount the udb device locks it up, preventing > ogfs locking mechanism to take effect .. > > > If you have any suggestion / better practice I would appreciate it You'll have to recompile UML. In UML's tree find arch/um/os-Linux/file.c. Locate the function int os_lock_file(int fd, int excl) and add: return(0); right after the {. Then compile as usual. :) This will disable locking so UML won't know when you have lunched more than one UML using the same "disk". If the filesystem isn't cluster-aware on both instances you'll loose data! Good luck, Nuno Silva |
From: roland <for...@gm...> - 2003-11-27 20:36:52
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hi! wouldn`t it be good to add an additional commandline param "nolock" to uml for this purpose, which makes os_lock_file() return(0) only if it is set to "yes"? so nobody needs to recompile, if he wants to use that "feature". just an idea..... regards roland ----- Original Message ----- From: "Nuno Silva" <nun...@vg...> To: <lup...@vi...> Cc: <use...@li...> Sent: Thursday, November 27, 2003 7:16 AM Subject: Re: [uml-user] Virtual shared resource > Hi! > > lup...@vi... wrote: > > > > I guess that the first UML host to mount the udb device locks it up, preventing > > ogfs locking mechanism to take effect .. > > > > > > If you have any suggestion / better practice I would appreciate it > > You'll have to recompile UML. In UML's tree find arch/um/os-Linux/file.c. > > Locate the function int os_lock_file(int fd, int excl) and add: > > return(0); > > right after the {. Then compile as usual. > > :) This will disable locking so UML won't know when you have lunched > more than one UML using the same "disk". If the filesystem isn't > cluster-aware on both instances you'll loose data! > > Good luck, > Nuno Silva > > > > > > ------------------------------------------------------- > This SF.net email is sponsored by: SF.net Giveback Program. > Does SourceForge.net help you be more productive? Does it > help you create better code? SHARE THE LOVE, and help us help > YOU! Click Here: http://sourceforge.net/donate/ > _______________________________________________ > User-mode-linux-user mailing list > Use...@li... > https://lists.sourceforge.net/lists/listinfo/user-mode-linux-user > |
From: Jeff D. <jd...@ad...> - 2003-12-05 23:52:40
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for...@gm... said: > wouldn`t it be good to add an additional commandline param "nolock" to > uml for this purpose, which makes os_lock_file() return(0) only if it > is set to "yes"? Yup. The locking is obviously a safety measure, but it makes sense to allow it to be turned off by people who claim to be doing locking themselves. Jeff |