Hi, Norbert, > Further question1: In fn isAvailable there is a part to find computers > whose hosts can handle the required RAM. Would not be necessary to have > something same for CPU?
The same is done for CPU count, CPU speed and network speed. You will notice in the query that the results will only include computers with specs greater than or equal to the image requirements. > FQ2: You mentioned ranking will be reversed (say Order by Asc in SQL query > part of > #image.OSid->OS.installtype->OSinstalltype.id->provisioningOSinstalltype.provisioningid->computer.provisioningid) > in the next major release so that computers > with the lowest specs will be ranked first. Is it better to keep the > computers with harder specs for future requests? There was a lengthier discussion of this on the dev list a few months ago [1] with some additional background. Best regards, Aaron [1] http://markmail.org/thread/d7jgat3buoah4mhe -- Aaron Coburn Systems Administrator and Programmer Academic Technology Services, Amherst College [email protected] > Thanks in advance, > Norbert > > > On 15 April 2013 15:01, Josh Thompson <[email protected]> wrote: > >> Norbert, >> >> Answers are inline. >> >> On Monday, April 15, 2013 8:29:34 AM Madarasz, Norbert wrote: >>> Hi all, >>> >>> This is the first time to write you. As part of my master's thesis at >>> Budapest University I should simulate the key functions of VCL with >>> CloudSim. >>> >>> For that the allocating logic is very important part means how a computer >>> is assigned to a reservation. I checked the cwiki page of VCL but the >> exact >>> procedure is not published. I've started to look inside the code and >> found >>> the predictive levels in PERL modules and it was understandable thanks to >>> vcld.log file which helped me to backtrace when, how and who called >> thoose >>> functions. >>> >>> Unfortunately this is not enough because the logic is missing how a >>> computer will be assigned to an image/reservation. As I saw this >> allocating >>> happens in Request.php (fn newReservation()) and maybe the main logic is >> in >>> Utils.php (fn allocComputer). >> >> You need to look at the isAvailable function in utils.php. That's where a >> computer is selected for any given reservation. >> >>> My problem is that there is no log that I can >>> use to backtrace what and when happening and I don't understand how this >>> allocating works. >> >> Correct - there is no log of how the computers are allocated. You can use >> the >> php function "error_log" to add your own logging to the isAvailable >> function >> to see what is happening. >> >>> Some questions: Is it random which available computer >>> will be used? If a computer is preloaded with the same image that a user >>> chose too then where and how will be taken this into account and filter >>> that computers which are preloaded with that image? >> >> By default, it is not random. Available computers are ordered first by >> whether or not they are currently loaded with the requested image, then by >> the >> specs of the computer with computers having the highest specs ranked first >> (however, that will be reversed in the next major release so that computers >> with the lowest specs will be ranked first). >> >> There is a config option in the conf.php file that will change the >> behavior so >> that computers are randomly assigned rather than being ranked by specs >> (they >> are still separated by preloaded/not preloaded). >> >>> What happens if a user >>> requests such an image that is not preloaded on any computer, is it >> problem >>> or only the provisioning time period will last a bit more? >> >> If a computer is not preloaded, it just makes the provisioning time longer. >> >>> Can someone explain the logic behind the allocating procedure and tell me >>> how the "computer-id" value of reservations table is calculated? >> >> See above. >> >>> Can you recommend me some technique to trace the "happenings" in php >>> scripts? I tried to use Zend Server instead of php5 server but there is >>> something wrong. Have you tried to use it with Zend Server, any >>> documentation or it shouldn't be problem? >> >> I've never used Zend Server. I'd recommend using the error_log function as >> described above. >> >>> Thank you in advance! >> >> You're welcome. >> >>> Best regards, >>> Norbert >> >> Josh >> >>> My advisor is Imre Kocsis and he suggested to mail here: >>> "Hi all, >>> >>> I am Norbert's advisor. Norbert, I think you should have posted this to >> the >>> 'dev' list rather than 'user'. Anyways, back in the summer when we >> started >>> getting our feet wet with VCL I managed to find only a short and >> incomplete >>> thread on the mailing list explaining the (largely undocumented) machine >>> allocation and preparation scheduling logic - so any help is greatly >>> appreciated. (Although based on our experience with the code base so far >> I >>> think the necessary information can be traced back from the source with >>> manageable effort.) >>> >>> To offer a bit of context to Norbert's questions: the larger goal is to >>> have a simple discrete event simulator for a hybrid VCL setup in order to >>> be able to play around with various reservation arrival processes, cost >> and >>> possibly fault models. (I know that 'hybrid' VCL setups - as in mixing an >>> in-house data center e.g. with EC2 - is not a technical reality for VCL >>> yet, but we are very interested in how it could work from the long-term >>> cost optimization and risk mitigation point of view for 'hardware budget >>> conscious' VCL setups.) >>> >>> After understanding the necessary parts of VCL, hopefully we will be able >>> to contribute some sort of documentation on (our understanding of) the >>> internals back to the community. >>> >>> Best regards >>> Imre" >> -- >> ------------------------------- >> Josh Thompson >> Systems Programmer >> Advanced Computing | VCL Developer >> North Carolina State University >> >> [email protected] >> 919-515-5323 >> >> my GPG/PGP key can be found at pgp.mit.edu >> >> All electronic mail messages in connection with State business which >> are sent to or received by this account are subject to the NC Public >> Records Law and may be disclosed to third parties.
