The first thing the node learns from the ma is its

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as the server trusts that the node is physically secure. The first thing the node learns from the MA is its current state . If the state = install , the boot manager runs an installer program that wipes the disk and down- loads the latest VMM, NM, and other required packages from the MA, and chain- boots the new kernel. The downloaded packages are also cached to the local disk. A newly installed node changes the node’s state at the database to boot so that subsequent attempts do not result in a complete re-install. If the node is in boot state, the boot manager generates a public-private key pair to be used in authenticating service slices once the node has booted (see Sec- tion 5.5), and requests that the MA generate a public key certificate that binds the public key to this particular node. It then contacts the MA to verify whether its cached software packages are up-to-date, downloads and upgrades any out-of-date packages, and finally chain-boots the most current kernel. Otherwise, if the boot manager learns that the node is in debug state, it continues to run the Linux kernel it had booted from the bootfile , which lets PLC operators ssh into and inspect the 21
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node. Both operators at PLC and the site technical contacts may set the node’s state (in the MA database) to debug or install , as necessary. In addition to boot-time, there are two other situations in which the node and MA synchronize. First, running nodes periodically contact the MA to see if they need to update their software, as well as to learn if they need to reinstall. Each node currently does this once a day. Second, whenever the node state is set to debug in the MA database, the MA contacts the node to trigger the boot process, making it possible to bring the node into a safe state very quickly. 4.9 Owner Script The PlanetLab architecture provides owners with as much autonomy as possible, even to those that offload responsibility for managing the node to PLC. Therefore, owners need some way to communicate how they want their nodes managed. For example, owners might want to prescribe what set of services (slices) run on their nodes, and allocate resources to one or more slice authorities for redistribution to slices. As described in Section 4.3, a designated VM named site admin is created on each node, and initialized with the keys belonging to the site’s technical and ad- ministrative contacts. An owner script running in this VM calls the node manager to express its preferences. Implementation Note: Today, owners confer their wishes out-of- band to PLC, which creates and installs an appropriate owner script on each node. Whether an owner script is edited remotely at PLC and later copied to each node, or the owner logs into its own node and directly edits the ownerscript is an implementation detail. The owner script typically allocates a set of resources to both slice authorities and to individual slices. It does this using the CreatePool( ) operation. The slice name given as an argument to CreatePool( ) identifies the slice that is allowed to retrieve the rcap and RSpec for the pool using the GetRcap( ) and GetRspec( ) calls, respectively. When allocating capacity to a slice creation service like
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