Archive for February, 2007

RaidZ discussion

Discussion on the pros and cons of raid-z vs mirroring: WHEN TO (AND NOT TO) USE RAID-Z from Bizarre ! Vous avez dit Bizarre.

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ZFS Best Practices Guide – Siwiki

Useful zfs guide: ZFS Best Practices Guide.

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zfs is cool!

I just installed Nexenta and I’ve been playing around with zfs. I must say the basic replication system is very cool. Seems to work for zvols as well. Remotely replicated iscsi volumes and nfs data sets, is going to make my backups trivial.

root@hzsilo:/tank/test# ls -l /tank/test2/
total 104
-rw-r--r-- 1 root root 104000 Feb 24 00:54 random
-rw-r--r-- 1 root root 104857600 Feb 24 01:00 random2

root@hzsilo:/tank/test# rm random2
root@hzsilo:/tank/test# zfs snapshot tank/test@10:00pm

root@hzsilo:/tank/test# zfs send -i tank/test@9:59pm tank/test@10:00pm | zfs receive tank/test2@10:00pm
cannot receive: destination has been modified since most recent snapshot

root@hzsilo:/tank/test# zfs rollback -r tank/test2@9:59pm
root@hzsilo:/tank/test# zfs send -i tank/test@9:59pm tank/test@10:00pm | zfs receive tank/test2@10:00pm
root@hzsilo:/tank/test# ls -l /tank/test2/
total 103
-rw-r–r– 1 root root 104000 Feb 24 00:54 random

For those of you who might have missed it, the send receive pipe could have a ‘ssh -C’ part as well. Brilliant. Plus because of the snapshots the deleted data is still there. The whole rollback thing is probably because of atime from the ls.

Some other stats from Wikipedia:

  • 248 — Number of snapshots in any file system (2 × 1014)
  • 248 — Number of files in any individual file system (2 × 1014)
  • 16 exabytes (264 byte) — Maximum size of a file system
  • 16 exabytes (264 byte) — Maximum size of a single file
  • 16 exabytes (264 byte) — Maximum size of any attribute
  • 3 × 1023 petabytes — Maximum size of any zpool
  • 256 — Number of attributes of a file (actually constrained to 248 for the number of files in a ZFS file system)
  • 256 — Number of files in a directory (actually constrained to 248 for the number of files in a ZFS file system)
  • 264 — Number of devices in any zpool
  • 264 — Number of zpools in a system
  • 264 — Number of file systems in a zpool

With that many snapshots possible you could almost have continue data protection. Even with 100 objects to snapshot at one per mintue; 144,000 snapshots, per day, it will be a long time before any limits are reached.

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Gizmo gets Flashed

This is quite clever. Using flash to build a zero-install voip  phone. No doubt we’ll be seeing phones this on corporate helpdesk pages in due course.

From: jkOnTheRun: Gizmo gets Flashed, makes calls from the browser

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128Gb Solid State Drive

Maybe in 5 years they’ll be cheaper, but affording one of these guys in the short term is going to be hard:

Okay, you know me well enough not to leave you hanging like that: a single 128GB Zeus SDD will set you back $50,000. Seriously. No word yet on discounts for bulk buying!

From: How about a 128GB Solid State HDD? and SimpleTech’s super-thin 64 GB SSD for those tight places.

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Polymer Vision to offer rollable eBook reader

From jkOnTheRun: Polymer Vision to offer rollable eBook reader. One of these will certainly make it easily to give an ebook to my mother.

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Red Hat vs. Microsoft: Who will win?

A little rant in following from: Red Hat vs. Microsoft: Who will win

The question I ask is why does Red Hat have to be as large as Microsoft?

Open Source allows everyone to share from each others work. It understands the implicit contract in computing that value creation in information is only occurs when it shared, a version of Metcalfe’s Law. In constrasted Closed Source understands that smaller groups controlling the flow and access to information and innovation allow these groups greater potential wealth.

After all how much would the network cost now, if we were running Microsoft or similar on our routers, servers and phones. Without Linux or BSD the freedom for choice, the ability to choice who innovates and thus allowing the market to decide who is better is removed.

So the innovation that is occurring and been driven in IT at the moment is because of OSS.

A clear example of this is Vmware, Xen and rPath.  Before the advent of Xen a company like rPath would likely have less reason to exist. There would be no software appliances. Vmware would still be printing money for its stock-holders. And for the man in the tench the vision of deploying a enterprise grade mail system like Zimbra in 30 minutes on a rPath platform would be hopeless.

It is not to say that I think huge companies are bad, but that freedom of choice it more vital. I think in the end on the balance of things, it is US all who will win.

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Jonathan Schwartz with Scoble

Jonathan is a very interesting guy, who seems to have a good vision for Sun. Its good to see an important tech company being lead by a visionary geek business leader, rather than just a business leader. Check out his blog as well.

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Virtual Iron short review

Exclusive: Virtual enlightenment through Xen

Moreover, Virtual Iron extends Xen by enhancing memory management to allow 32-bit and 64-bit guests to run side-by-side, full virtualization to allow guest OSes to run completely unmodified (the current Xen release requires the guest OSes to be modified to run in a Xen environment), and significant work to increase I/O performance of guest OSes. These features will be present in the forthcoming Xen 3.1 release, but Virtual Iron is offering them now, with the GUI management tools.

On the downside, there’s no iSCSI SAN or NFS support, so if you’re lacking a Fiber Channel SAN, you’re forced to use local disk, and this precludes the use of the LiveMigration, LiveRecovery, and LiveMaintenance features.

So what’s lacking? Polish, performance, and the little bits around the edges. The console interaction provided by Virtual Iron 3.1 is fair for Windows guests, but quite sloppy for Linux guests running X11. This is rather surprising, but mouse tracking under Windows is far superior. Of course, most Linux guests won’t be running X11, which mitigates this problem somewhat.

Also missing is VM snapshot support, as well as basic backup tools. Coupled with the lack of iSCSI and NFS support, very basic network configurations, questionable I/O performance, and the obvious wet-behind-the-ears feel of the package, it may be a bit of a hard sell for production use.

Also looks like Virtual Iron lacks vlan support at the moment. Lack of this and iSCSI/NFS restricting shared storage to Fibre is going to cut out a lot of potential users. Especially in the SMB market. Its strange as there storage subsystem seems like its layered on top of LVM with Microsoft based VHD files in logical volumes (LV). You would think that it was easy enough to engineer iSCSI by replacing the Fibre device blocks with iSCSI device blocks on the processing nodes.

Without the LiveMigration support Virtual Iron isn’t really that much better than Xen. They will also have to increase their systems supported coverage for Linux to Debian/Ubuntu for both there management and vmtools.

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Virtual Iron

Check this webcast hosted by PlateSpin and Virtual Iron: Reducing Costs and Increasing Agility with Virtualization, and this interface demo. Unfortunately you have to sign up to see it, however it shows some similar stuff to the VI3 demo further down this blog. Virtual Iron is Xen based with some of their own additions, they have Live Migration and DR Migration working now, plus there management interface is very nice.

The one feature I think is perfect and I’ve thought about doing myself is PXE booting the computing nodes and having them join the computing cluster as a resource automagically. This is exactly the right idea. The hardware platform you are running on reduces down to just a software management system. No doubt within a few years server systems will start being designed with the option of a hypervisor as part of the bios. Some one clever could probably do it now with LinuxBios.

The Virtual Iron price structure is very similar to Xen, and beats VMware’s by a huge margin. 500USD plus 125USD per year vs 2875USD per socket plus 700USD per year.

Some other useful info on Virtual Iron:

I’ve been deciding between VMWare and Xen recently for a server upgrade, but I think that Virtual Iron might be the right choice. Xen flexibility with VMWare’s features.

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