Thursday Feb 01, 2007

Well, the Good Wine's A-Flowin'



Jerry has posted an excellent summary of the work he and Steve Lawrence architected as part of Project Duckhorn. The project encompassed a number of new features which are detailed here (see the quoted proposal in Jeff Victor's message), here and here. As Jerry discusses, zones and OpenSolaris resource management previously could be combined but it required quite a bit of knowledge to integrate these technologies together. The team was able to define some sensible yet powerful abstractions that really bring to fruition the notion of a container.

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Tuesday Jan 09, 2007

Privilege (Set Me Free)



One of the perhaps lessor known features of Solaris Containers or Zones is that applications running inside these virtualized environments execute with less privileges than applications executing outside the container. This is enforced through the Solaris Privileges framework which was also introduced in the Solaris 10 release.

When comparing virtualization solutions, typically OS level virtualization mechanisms like Zones or FreeBSD Jails are thought to provide less security than mechanisms where a machine architecture is virtualized, such as with the family of products from VMware or with paravirtualization mechanisms such as Xen, in which the guest OS is ported to the virtualized machine architecture. One reason for that is there is usually weaker separation between virtualized OS environments since at several levels in the kernel there is some sharing of data structures and code paths.

However in some cases, OS level virtualization provides an advantage for certain aspects of security. For example, with Solaris Containers the privilege mechanism in the kernel enforces limitations on the types of operations an application can perform. Consider the case of the ability to create or "plumb" a software networking interface using ifconfig(1M) or set an IP address on that interface. In some situations, one wants to allow such operations inside a virtualized environment because a particular application requires the ability to change an existing IP address or to toggle an interface up or down. The ramification of this, however, is that a malicious or naive user inside the environment might change their IP address to something not expected with the results ranging from disruption in the network topology to the potential of spoofing another machine on the network. In addition, most applications do not actually require the ability to change their environment's IP address or create new network interfaces or even know the name of the interface in their environment. Rather, they typically want one or more IPv4 or IPv6 addresses which they can bind(3SOCKET) to.

In the case of Solaris Containers, the privilege to set the IP address of an interface is not given to any applications running inside a container and there is no way for an application to escalate or grow the set of privileges from those they started out with. The end result, in this example, is that the root password or super-user privileges can be given to a user inside a container but they will be unable to manipulate or affect the topology of the network or impersonate another machine and potentially gain access to its network traffic.1

Until recently, the set of privileges a container's applications were limited to was fixed. However starting with both Solaris Express 5/06 and Solaris 10 11/06, the global zone administrator can change this set of privileges. What this means from a practical point of view is that containers can become more capable by adding some of the privileges that are not usually present. An example here might be the ability to run DTrace from within the container2. Dan provided an excellent writeup on the details for doing so here.

As another example, by adding some additional privileges to the container's default privilege set, a Network Time Protocol (NTP) server can be deployed in the container which is preferable from a security point of view, especially for a server that might be facing a hostile Internet. In order to configure the container appropriately, the list of privileges that it requires needs to be known. Solaris 10 currently ships with the 3-5.93e version of xntpd(1M), which is the daemon that implements the NTP server capability. This particularly daemon actually can take advantages of three privileges that are not normally present within a container. The first, perhaps obviously, is the privilege to change the system clock - sys_time. With the addition of this privilege, xntpd will be able to successfully set the system clock when it needs to.

However it also turns out that the daemon tries to both lock down its memory pages and also run in the real-time scheduling class. It does this so that the daemon can maintain accurate time particularly in the face of other system activity. These two operations are also covered by unique privileges - proc_lock_memory and proc_priocntl.

Tying these privileges3 together, we can take an existing container and configure it to be a NTP server. In this example, Sun's internal network routes IP multicast and so I will leverage that to connect to the network's NTP servers listening on the standard multicast address of 224.0.1.1 for NTP: For example, consider this update to the configuration of the zone myzone:
        global# zonecfg -z myzone
        zonecfg:myzone> set limitpriv=default,proc_lock_memory,proc_priocntl,sys_time
        zonecfg:myzone> commit
        zonecfg:myzone> exit
        global# zoneadm -z myzone boot

Then from within the newly booted container, I will set up the configuration of the server itself and start the service:

        myzone# cp -p /etc/inet/ntp.client /etc/inet/ntp.conf
        myzone# svcadm enable network/ntp

The property that was set in the container's configuration, limitpriv, consists of a list of privileges similar to the form expected by user_attr(4) and priv_str_to_set(3C). In this particular example, the container's privilege set is limited to the standard default set of privileges plus the three additional privileges required by the NTP server.

It is worthwhile to note that privileges can also be taken away by preceding them with an exclamation mark (!) or a minus sign (-). This can allow a container to be booted in which applications have even fewer privileges than usual. For example, to take away the ability to generate ICMP datagrams from the zone named twilight, the global zone administrator would configure the container as follows:

        global# zonecfg -z twilight set limitpriv=default,!net_icmpaccess

There are a few restrictions on what privilges can be added to a container as well as some concerning which ones can be removed. For more details, please see the original proposal and the ensuing discussion on the zones-discuss mailing list. This proposal and many others concerning containers and other parts of OpenSolaris have benefited greatly from the participation of the OpenSolaris Zones Community. Information about each of these proposals can be found here.


1 The actual privilege check in the kernel for this particular case occurs here.

2 The ability to use DTrace inside a non-global zone is at the present time restricted to Solaris Express as some additional changes to DTrace were required. However, these changes should be appearing in an upcoming Solaris 10 release.

3 Starting with Solaris Express 11/06, the privilege to lock memory has actually been added to the container's default set. This is because additional resource controls have been added that can limit the amount of memory applications within a container can lock so it is no longer necessary to make this privilege an optional one.


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Monday Sep 12, 2005

Three Conductors and Twenty-five Sacks of Mail



I would like to thank everyone that came out to the Silicon Valley OpenSolaris Users Group (SVOSUG) meeting on August 31st and for bearing with me as we struggled with getting the laptop and projector to play nice with one another. The slides for the presentation are now available.

The questions and feedback on Zones were excellent and it was great to see the level of interest in OpenSolaris. Special thanks to Dan and Allan of the Zones project team for taking notes and lending support and of course, to the other Alan for all his work in organizing the meetings.

One frequently asked question which came up at the meeting is how can a zone support a writable directory under /usr, such as /usr/local, when the former is usually mounted read-only from the global zone.

The easiest way to support such a directory is to add a lofs(7FS) file system for the zone using zonecfg(1M). One simply needs to specify a directory in the global zone to serve as backing store for the zone's /usr/local directory and then edit the zone's configuration as follows:

        global# mkdir -p /usr/local
        global# mkdir -p /path/to/some/storage/local/twilight
        global# zonecfg -z twilight
        zonecfg:twilight> add fs
        zonecfg:twilight:fs> set dir=/usr/local
        zonecfg:twilight:fs> set special=/path/to/some/storage/local/twilight
        zonecfg:twilight:fs> set type=lofs
        zonecfg:twilight:fs> end
        zonecfg:twilight> commit
        zonecfg:twilight> exit
        global#

The next time the zone boots, it will have its own writable /usr/local directory.

Speaking of frequently asked questions, Jeff has compiled a Zones and Containers FAQ which provides a list of the common questions that have been asked since Zones were introduced along with their answers. The FAQ along with a great deal of other information can also be found on the redesigned OpenSolaris Zones Community page, which was recently given a well needed makeover by Dan.


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Monday Aug 29, 2005

Lastly Through a Hogshead of Real Fire!



Tomorrow evening, August 30th at 7:30, at the Silicon Valley OpenSolaris Users Group (SVOSUG) meeting, I will have the pleasure of talking about Zones, the virtualization software available in OpenSolaris. This month's meeting will be held upstairs from the auditorium at Sun's Santa Clara campus - directions are available .

In addition to the talk (for which I will post slides soon), there will be a panel discussion to discuss anything related to OpenSolaris and hopefully there will be a status update of where things stand, which build has been released and other related news.

Thanks again to Alan for organizing these meetings and to the community for attending and bringing their questions, concerns and enthusiasm. We look forward to seeing you at the user group meeting.

This is a stereo recording.
A splendid time is guaranteed for all.


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Tuesday Jun 14, 2005

These Boots are Made for Walkin'



One of the most gratifying and exciting aspects of the OpenSolaris project is a return (for me, at least) to working on operating system design and research with the larger, open community. In another era while I was an undergraduate at Berkeley, I was fortunate enough to see the 2.x and 4.x BSD development effort up close and to see the larger community formed between the University and external organizations that had UNIX source licenses. It was not an open source community, of course, but it was a community none the less, and one that shared fixes, ideas and other software projects built on top of the operating system. Our hopes for OpenSolaris are that in addition to releasing operating system source code that can be used for many different purposes, Sun and the community will innovate together while maintaining the core values that Solaris provides today.

One of the many pieces of OpenSolaris which is of personal interest is the Zones virtualization technology introduced in Solaris 10. Zones provide a lightweight but very efficient and flexible way of consolidating and securing potentially complex workloads. There is a wealth of technical information about Zones in Solaris available at the OpenSolaris Zones Community and the BigAdmin System Administration Portal.

One of the things about Zones that people notice right away is how quickly they boot. Of course, booting a zone does not cause a system to run its power-on self-test (POST) or require the same amount of initialization that takes place when the hardware itself is booting. However, I thought it might be useful to do a tour of the dance that takes place when a non-global zone is booted. I call it a dance since there is a certain amount of interplay between the primary players - zoneadm, zoneadmd and the kernel itself - that warrants an explanation.

Although the virtualization that Zones provides is spread throughout the source code, the primary implementation in the kernel can be found in zone.c. As with many OpenSolaris frameworks, there is a big block comment at the start of the file which is very useful for understanding the lay of the land with respect to the code. Besides describing the data structures and locking strategy used for Zones, there is a description of the states a zone can be in from the kernel's perspective and at what points a zone may transition from one state to another. For brevity, only the states covered during a zone boot are listed here

 ...
 \*
 \*   Zone States:
 \*
 \*   The states in which a zone may be in and the transitions are as
 \*   follows:
 \*
 \*   ZONE_IS_UNINITIALIZED: primordial state for a zone. The partially
 \*   initialized zone is added to the list of active zones on the system but
 \*   isn't accessible.
 \*
 \*   ZONE_IS_READY: zsched (the kernel dummy process for a zone) is
 \*   ready.  The zone is made visible after the ZSD constructor callbacks are
 \*   executed.  A zone remains in this state until it transitions into
 \*   the ZONE_IS_BOOTING state as a result of a call to zone_boot().
 \*
 \*   ZONE_IS_BOOTING: in this shortlived-state, zsched attempts to start
 \*   init.  Should that fail, the zone proceeds to the ZONE_IS_SHUTTING_DOWN
 \*   state.
 \*
 \*   ZONE_IS_RUNNING: The zone is open for business: zsched has
 \*   successfully started init.   A zone remains in this state until
 \*   zone_shutdown() is called.
 ...

It is important to note here that there are a number of zone states not represented here - those are for zones which do not (yet) have a kernel context. An example of such a state is for a zone that is in the process of being installed. These states are defined in libzonecfg.h.

One of the players in the zone boot dance is the zoneadmd process which runs in the global zone and performs a number of critical tasks. Although much of the virtualization for a zone is implemented in the kernel, zoneadmd manages a great deal of a zone's infrastructure as outlined in zoneadmd.c

/\*
 \* zoneadmd manages zones; one zoneadmd process is launched for each
 \* non-global zone on the system.  This daemon juggles four jobs:
 \*
 \* - Implement setup and teardown of the zone "virtual platform": mount and
 \*   unmount filesystems; create and destroy network interfaces; communicate
 \*   with devfsadmd to lay out devices for the zone; instantiate the zone
 \*   console device; configure process runtime attributes such as resource
 \*   controls, pool bindings, fine-grained privileges.
 \*
 \* - Launch the zone's init(1M) process.
 \*
 \* - Implement a door server; clients (like zoneadm) connect to the door
 \*   server and request zone state changes.  The kernel is also a client of
 \*   this door server.  A request to halt or reboot the zone which originates
 \*   \*inside\* the zone results in a door upcall from the kernel into zoneadmd.
 \*
 \*   One minor problem is that messages emitted by zoneadmd need to be passed
 \*   back to the zoneadm process making the request.  These messages need to
 \*   be rendered in the client's locale; so, this is passed in as part of the
 \*   request.  The exception is the kernel upcall to zoneadmd, in which case
 \*   messages are syslog'd.
 \*
 \*   To make all of this work, the Makefile adds -a to xgettext to extract \*all\*
 \*   strings, and an exclusion file (zoneadmd.xcl) is used to exclude those
 \*   strings which do not need to be translated.
 \*
 \* - Act as a console server for zlogin -C processes; see comments in zcons.c
 \*   for more information about the zone console architecture.
 \*
 \* DESIGN NOTES
 \*
 \* Restart:
 \*   A chief design constraint of zoneadmd is that it should be restartable in
 \*   the case that the administrator kills it off, or it suffers a fatal error,
 \*   without the running zone being impacted; this is akin to being able to
 \*   reboot the service processor of a server without affecting the OS instance.
 \*/

When a user wishes to boot a zone, zoneadm will attempt to contact zoneadmd via a door that is used by all three components for a number of things including coordinating zone state changes. If for some reason zoneadmd is not running, an attempt will be made to start it. Once that has completed, zoneadm tells zoneadmd to boot the zone by supplying the appropriate zone_cmd_arg_t request via a door call. It is worth noting that the same door is used by zoneadmd to return messages back to the user executing zoneadm and also as a way for zoneadm to indicate to zoneadmd the locale of the user executing the boot command so that messages are localized appropriately.

Looking at the door server that zoneadmd implements, there is some straightforward sanity checking that takes place on the argument passed via the door call as well as the use of some of the technology that came in with the introduction of discrete privileges in Solaris 10.

	if (door_ucred(&uc) != 0) {
		zerror(&logsys, B_TRUE, "door_ucred");
		goto out;
	}
	eset = ucred_getprivset(uc, PRIV_EFFECTIVE);
	if (ucred_getzoneid(uc) != GLOBAL_ZONEID ||
	    (eset != NULL ? !priv_ismember(eset, PRIV_SYS_CONFIG) :
	    ucred_geteuid(uc) != 0)) {
		zerror(&logsys, B_FALSE, "insufficient privileges");
		goto out;
	}

	kernelcall = ucred_getpid(uc) == 0;

	/\*
	 \* This is safe because we only use a zlog_t throughout the
	 \* duration of a door call; i.e., by the time the pointer
	 \* might become invalid, the door call would be over.
	 \*/
	zlog.locale = kernelcall ? DEFAULT_LOCALE : zargp->locale;

Using door_ucred, the user credential can be checked to determine whether the request originated in the global zone,1 whether the user making the request had sufficient privilege to do so2 and whether the request was a result of an upcall from the kernel. That last piece of information is used, among other things, to determine whether or not messages should be localized by localize_msg.

It is within the door server implemented by zoneadmd that transitions from one state to another take place. There are two states from which a zone boot is permissible, installed and ready. From the installed state, zone_ready is used to create and bring up the zone's virtual platform that consists of the zone's kernel context (created using zone_create) as well as the zone's specific file systems (including the root file system) and logical networking interfaces. If a zone is supposed to be bound to a non-default resource pool, then that also takes place as part of this state transition.

When a zone's kernel context is created using zone_create, a zone_t structure is allocated and initialized. At this time, the the status of the zone is set to ZONE_IS_UNINITIALIZED. Some of the initialization that takes place is in order to set up the security boundary which isolates processes running inside a zone. For example, the vnode_t of the zone's root file system, the zone's kernel credentials and the privilege sets of the zone's future processes are all initialized here.

Before returning back to the zoneadmd command, zone_create adds the primordial zone to a doubly-linked list and two hash tables, 3 one hashed by zone name and the other by zone ID. These data structures are protected by the zonehash_lock mutex which is then dropped after the zone has been added. Finally a new kernel process is then created, zsched, which is where kernel threads for this zone are parented. After calling newproc to create this kernel process, zone_create will wait using zone_status_wait until the zsched kernel process has completed initializing the zone and has set its status to ZONE_IS_READY.

Since the user structure of the process initialization has not been completed, the first thing the new zsched process does is finish that initialization along with reparenting itself to PID 1 (the global zone's init, process). And since the future processes to be run within the new zone may be subject to resource controls, that initialization takes place here in the context of zsched.

After grabbing the zone_status_lock mutex in order to set the status to ZONE_IS_READY, zsched will then suspend itself, waiting for the zone's status to been changed to ZONE_IS_BOOTING.


Once the zone is in the ready state, zone_create returns control back to zoneadmd and the door server continues the boot process by calling zone_bootup This initializes the zone's console device, mounts some of the standard OpenSolaris file systems like /proc and /etc/mnttab and then uses the zone_boot system call to attempt to boot the zone.

As the comment that introduces zone_boot points out, most of the heavy lifting has already been done either by zoneadmd or by the work the kernel has done through zone_create. As this point, zone_boot saves the requested boot arguments after grabbing the zonehash_lock mutex and then further grabs the zone_status_lock mutex in order to set the zone status to ZONE_IS_BOOTING. After dropping both locks, it is zone_boot that suspends itself waiting for the zone status is be set to ZONE_IS_RUNNING.


Since the zone's status has now been set to ZONE_IS_BOOTING, zsched now continues where it left off after it has suspended itself with its call to zone_status_wait_cpr After checking that the current zone status is indeed ZONE_IS_BOOTING, a new kernel process is created in order to run init in the zone. This process calls zone_icode which is analogous to the traditional icode function that is used to start init in the global zone and in traditional UNIX environments. After doing some zone-specific initialization, each of the icode functions end up calling exec_init to actually exec the init process after copying out the path to the executable, /sbin/init, and the boot arguments. If the exec is successful, zone_icode will set the zone's status to ZONE_IS_RUNNING and in the process, zone_boot will pick up where it had been suspended. At this point, the value of zone_boot_err indicates whether the zone boot was successful or not and is used to set the global errno value for zoneadmd.

There are two additional things to note with the zone's transition to the running state. First of all, audit_put_record is called to generate an event for the Solaris auditing system so that it's known which user executed which command to boot a zone. In addition, there is an internal zoneadmd event generated to indicate on the zone's console device that the zone is booting. This internal stream of events is sent by the door server to the zone console subsystem for all state transitions, so that the console user can see which state the zone is transitioning to.


1 This is a bit of defensive programming since unless the global zone administrator were to make the door in question available through the non-global zone's own file system, there would be no way for a privileged user in a non-global zone to actually access door used by zoneadmd.

2 zoneadm itself checks that the user attempting to boot a zone has the necessary privilege but it's possible some other privileged process in the global zone might have access to the door but lack the necessary PRIV_SYS_CONFIG privilege.

3 The doubly-linked list implementation was integrated by Dave while Dan was responsible for the hash table implementation. Both of these are worth examining in the OpenSolaris source base.


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Thursday Aug 26, 2004

The Pump Don't Work 'Cause the Vandals Took the Handles



Whether you are trying to figure out why the pump "don't work" or you are trying to protect the pump from the iVandals out in the real world, Solaris 10 can help you deal with these and many other situations. DTrace is known as the technology which provides concise answers to arbitrary questions. It has been used within Sun and by our customers to improve the performance of the operating system and applications alike and to help find the root cause of bugs which previously were difficult, if not near impossible to find using traditional debugging techniques. It allows such analysis, safely, on production systems without requiring recompilation of the operating system or the application and without having to recreate the production environment where a problem has been observed.

Zones can help isolate application environments from one another such that even if one becomes a privileged user in one of the application environments, the damage one can cause on purpose or inadvertently is isolated to that one zone or container. The degree of isolation is such that each zone can be rebooted independently without affecting any other zones on the system or the machine as a whole (and the zones boot very quickly - for example, on a Sun Fire V60x a zone can boot in as little as eight seconds, from a halted state to login prompt.)

Finally, the Predictive Self-Healing technology can help customers maximize the availability of their computing resources, and to handle faults that may occur whether in software or in hardware. In the past, typically problems resulted in a number of messages appearing in the system log which left both customers and often service personnel scratching their heads, trying to make sense of these symptoms. Predictive Self-Healing instead observes generated error events or telemetry and once sufficient telemetry has been been obtained, diagnosis engines can generate a single fault event to agents which can respond to the diagnosed fault.

Not too long ago, a number of engineers who designed these new frameworks participated in three Sun Expert Exchanges where over a live chat system we were able to answer technical questions about these features and get valuable feedback from customers. The transcript of the DTrace exchange in which Adam and Bryan and others participated can be found here. About a month later, Andy and Dan and I participated in an exchange on Zones which not only was a great deal of fun but provided us with a lot of interesting input and we hope was helpful to both current zones users and interested parties alike. The transcript for that exchange is available here. And about a week ago, some of the architects of the Predictive Self Healing functionality participated in their own exchange and its transcript is available here.

Transcripts from other Expert Exchanges are available as well here under Archives and registration is open for a number of other planned sessions including one on ZFS (The Zettabyte Filesystem) and the many fundamental security enhancements that have been made to Solaris 10.

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Friday Aug 06, 2004

What's New Pussycat?



Support for Zones was initially released in the Software Express for Solaris 2/04 release. Since then, we have been working on adding a number of enhancements as well as fixing a number of bugs that have been reported. Of course, the definitive source for what has changed in each of the Solaris releases can be found in that release's Solaris What's New document. However, I thought it might be useful to summarize the Zones enhancements that have been released since February and what is coming in the upcoming Software Express for Solaris release.

In the Software Express for Solaris 7/04 release, support for Zones being NFSv4 clients was added. In that particular build, the default NFS version was still three (3) but this can be changed by editing the file /etc/default/nfs and uncommenting and changing the NFS_CLIENT_VERSMAX parameter to 4. For more information, please see the nfs(4) manual page. Note that in the upcoming Software Express for Solaris release, the default NFS version will be four (4) although the system will negotiate a lower version as necessary.

On a similar note, the statistics reported by nfsstat(1M) have been virtualized on a per-zone basis.

With the power of the Tecla command-line editing library, the zonecfg(1M) command now supports command line editing, command history and tab completion within interactive mode. This new functionality can make it far easier to enter or edit a zone's configuration. In addition, each user can customize their own particular set of key bindings through the file .teclarc in their home directory.

One of the other new features in this release is the ability to specify a richer set of file systems through zonecfg(1M) Previously, the administrator could specify a restricted set of file systems such as lofs(7FS) or tmpfs(7FS). This restriction to a large degree is lifted in this release, allowing the administrator to specify file systems like ufs(7FS).

For example, consider this update to the configuration of the zone myzone:
        global# zonecfg -z myzone
        zonecfg:myzone> add fs
        zonecfg:myzone:fs> set dir=/source
        zonecfg:myzone:fs> set special=/dev/md/dsk/d4
        zonecfg:myzone:fs> set raw=/dev/md/rdsk/d4
        zonecfg:myzone:fs> set type=ufs
        zonecfg:myzone:fs> end
        zonecfg:myzone> commit
        zonecfg:myzone> exit
        global#

What we have added to the configuration is a UFS file system that will automatically be mounted as /source when the zone is booted. The partition used is a Solaris Volume Manager metadevice that was created and initialized from within the global zone.

Finally, the Software Express for Solaris 7/04 release includes two enhancements to the ps(1) command to add zone information to any current command output and to filter information based on one or more zones. The new -Z option adds a ZONE column to any report generated by ps(1) while the -z zidlist option prints only those processes belong to the zones specified in the comma-separated zidlist (zones can be listed either by name or by their ID number.)

In the upcoming Software Express for Solaris release, there are three additional enhancements being introduced for Zones. As a teaser, I will briefly describe them now and cover them later in more depth when the release is made available.

When resource pools have been enabled, the first enhancement more accurately reports the processor resources available to a zone and their statistics as reported by commands such as iostat(1M) , mpstat(1M) , vmstat(1M) , psrinfo(1M) and sar(1). In a similar manner, library routines such as getloadavg(3C) and sysconf(3C) (the latter when invoked for _SC_NPROCESSORS_CONF or _SC_NPROCESSORS_ONLN) only return information for the processors in the set a particular zone is bound to.

In addition, a new resource control has been introduced, zone.max-lwps, which allows a global zone administrator to limit the number of lightweight processes or LWPs that can be created inside a zone. From within the zone itself, another new resource control, project.max-lwps, can be used to further divide the total number of LWPs amongst the projects defined in the zone.

Finally, Solaris Auditing can now be configured for zones in a number of different ways. The global zone administrator can specify whether the whole system should be audited as a whole or whether each zone can be audited separately. In the latter case, each zone has its own audit configuration and that zone's administrator can configure and process their audit trails independently from the other zones on the system.

We welcome hearing about your experiences or problems with using Zones and of any feature enhancements you would like to see.


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Tuesday Aug 03, 2004

Begin the Beguine



To be perfectly honest, it is with some trepidation that I have started this blog. While I marvel at this new opportunity to be a part of these conversations with the various Sun communities, I worry that it will be difficult time-wise to stay involved. Perhaps I also share some of the feelings expressed by Casper when he says that that it feels like talking into thin air. In any case, this is a wonderful opportunity for all of us to hear from you about what concerns you have and how we can make Solaris that nexus of innovation as well as a way of solving your computing needs.

Briefly, I have been working at Sun on Solaris for a little over eight years now, initially in the networking group responsible for the TCP/IP stack and related technologies and for the past couple of years, in the area of server virtualization and resource management working inside a group with Andy and Dan and a number of others in introducing Zones into Solaris.

Zones provide a new operating system abstraction for partitioning systems so that multiple applications can be run in isolation from one another, while perhaps being administered by different privileged users. It borrows in a number of ways from the concepts introduced by FreeBSD Jails but extends it to be full integrated with the features that Solaris offers. In my opinion, the most exciting point of integration is with the Solaris Resource Management framework which was introduced in Solaris 8 and greatly enhanced in Solaris 9 and 10 because combined they provide the necessary characteristics to fully isolate applications and workloads from one another. Together, these two technologies form the basis of N1 Grid Containers which are supported on all system that Solaris supports, from single-processor x86 laptops, to large, multi-processor servers.

For a brief but semi-technical overview of Solaris Zones, a good starting point is the paper we presented at a work-in-progress session at the recent USENIX VM '04 conference. For more information in general about Zones, the Zones BigAdmin site provides a great deal of information including a pointer to the latest documentation on these technologies and an active discussion forum. And to repeat a popular refrain, we encourage you to not just read about Zones and the other new functionality in Solaris 10, but to experience it yourself by downloading it from the Software Express for Solaris site.

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Today