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Not quite zfs needs to contact the destination zfs fs to compare with the last snapshot

Ehm, no, sorry. No communication with the destination machine is required while generating an incremental send stream. How can I claim this? Well besides being quite intimate with the ZFS source base (and I can point you to the relevant source files if you so desire), just a quick read through the zfs(1M) manpage will mention this example:

# zfs send pool/fs@a | ssh host zfs receive poolB/received/fs@a

As you are no doubt aware, pipes are by definition unidirectional. There is no way the zfs receive can talk to the zfs send at all. Another way to verify this is to check out ZFS backup systems such as Zetaback, which by default store the ZFS send streams as files on a central server (which may or may not actually support ZFS - it's not actually required). Now if an incremental send stream is stored as a file and then at some later point restored, this clearly tells you that there can't be any bidirectional exchange of information going on.

OpenSolaris is old and discontinued. OpenIndiana is a CDDL fork of OpenSolaris, rebased onto what's now called Illumos (http://illumos.org/), and is one of several Illumos "distros".

OpenIndiana was meant to be an answer to desktop Linux. It did not do especially well in terms of uptake, for reasons related to Linux's desktop results. However, there are a variety of other distros which are more server-oriented, and they are fairly popular.

They include for example SmartOS (used by http://joyent.com/ for multitenant hosting and for their own software development), OmniOS (used for mainly single-tenant hosting, and for software development http://omniti.com/), Nexenta (used for building large storage systems), and Delphix (a data storage service).

They all rely on the debuggability of Illumos (mdb, dtrace), virtualization (zones, now including Linux branded zones, crossbow, kvm), services (NFS and iSCSI in particular, also various others like SMB), OpenZFS, and a variety of other useful features, such as even under light use making enormous use of threading for parallelism and concurrency (and the threading systems scale well; OpenZFS alone typically uses a couple thousand threads, hundreds of thousands of mutexes, and many condvars, and all will go higher with load; other kernel subsystems can be similar).

It's fairly common for computer services departments in universities and laboratories and so forth to use e.g. an OmniOS server in front of a large storage pool, offering up iSCSI, NFS and other shares to clients, or alternative SmartOS in front of a large storage pool, offering up lightweight VMs to clients.

Oracle's Solaris has diverged from Illumos (and vice-versa). The key features are similar, but Oracle has been targeting much higher-end applications -- much larger and busier storage pools, especially ones which are very heavily random-acess (big Oracle databases are an application). Like Illumos, it can run very well on hardware with huge numbers of cores (including hyperthread-like cores). Unlike Illumos, it's not developed in the open (and is not open source), but it is well-supported enough that expensive contracts get you fixes and sometimes features quickly. Illumos has been slower until fairly recently, for reasons including the lack of ability to do a fully self-hosted build (it relied on nonstandard build tools), an idiosyncratic source code repository, both of which have now been changed in the past few weeks.

If you're already running Solaris 11, and you're sick of Oracle's shenanigans, you might find a transition to OmniOS to be surprisingly painless. OmniTI doesn't grind up small children with their coffee beans like Larry Ellison does, either. Their work is completely Open Sourced so you can participate in improving the free operating system, and pay for support, hosting, etc.

OmniOS is based on illumos (kind of like RHEL is based on Linux & GNU). There are a number of other illumos distributions besides OmniOS that are worth a good serious look. Get out of bed with Oracle, already.

The illumos project provides the basis for a Solaris-like operating system. Many distributions of illumos are now available, just like Linux. I think OmniOS and SmartOS are particularly worthy of your consideration, and ready for enterprise-scale production use, big data, DevOps, and all the other buzzwords.

I use Nagios and some custom rolled scripts myself.

For some other options, Nagios has now been forked, so if that is "close" to what you want, you may want to contribute to Icinga.

Reconnoiter also looked pretty kewl, but they haven't released anything yet, but it looks like they are planning it to be very scalable.

This sounds like OmniTI. We even have a kegerator in the break room. Only we're not a startup, we do fun Internetty stuff and we've been profitable every year since inception. Go figure!

Shouldn't everyone have perks like these?

I didn't even know there was a SPECmail, but this figure doesn't seem too outstanding to me.

Firstly I assume this is just a raw delivery setup - no spam or virus filtering. You'd be amazed how much of a difference this makes to any real world setup.

Secondly, apache.org does over 2 million mails a day on a dual 2.4Ghz Xeon using an SMTP server written in Perl. And that's with full anti-virus (clamav) and lots of different anti-spam measures including SpamAssassin (which is known to be slow - I know because I used to be one of the developers).

I also know of commercial setups doing over 50m (legit, well - mostly) mails a day. Using an SMTP Server designed with performance in mind. Perhaps they should submit for SPECmail ;-)

So 30 million doesn't seem terribly amazing to me. Perhaps Communigate Pro isn't a very fast mail server.

The reality is that the differences are really minor, and, now that RSA is legal, openssh can be setup to act almost exactly the same as closedssh.

The only signicant difference between them for most peole is the price.

There used to be a fair bit of difference, but at least for unix, this is no longer true. Since 2.5 openssh has supported sftp. Since 3.0 it supports rekeying a session. With external PAM modules you can support smart cards and securid logins.

The one advantage that ssh has over openssh is that this is all integrated into one package. The smartcard support is built in, you don't have to go looking for support.

If you are not planning on using smartcards or tokens, then openssh wins based on price alone. You can get it pre-compiled for most platforms, so the compilation is not so much the issue. Otherwise you have to weigh the choices a little more carefully. Check to see if your required token/card is supported by both. If not, then it is likely to be easier to add support into openssh, having the source and all.

In terms of windows clients...that is one big differentiator. Again, mostly money! We use tera-term and that works quite well, but does not do ssh V2 protocols.

In either case, you are buying a big whack of security, but don't forget, passwords can be extremely weak! Don't let up on the other security policies just because you now have SSH. (And yes, I know that the poster is not responsible for this, this is just a general admonition :-)

Whatever you get, I wish you the best of luck.

Now for the gratuitous links: :-)

securid and openssh

some preliminary smartcard itegration with openssh

another smartcard and openssh link