ZFS Disk Mirroring, Striping and RAID-Z

This is the third in a series of tests (( the previous ones are ZFS on Linux Works! and ZFS versus XFS with Bonnie++ patched to use random data )), but this time we’re going to test out how it handles multiple drives natively, rather than running over an existing software RAID+LVM setup. ZFS has the ability to dynamically add disks to a pool for striping (the default) mirroring or RAID-Z (with single or double parity) which are designed to improve speed (with striping), reliability (with mirroring) and performance and reliability (with RAID-Z).

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ZFS versus XFS with Bonnie++ patched to use random data

I’ve patched Bonnie++ (( it’s not ready for production use as it isn’t controlled by a command line switch and relies on /dev/urandom existing )) to use a block of data from /dev/urandom instead of all 0’s for its block write tests. The intention is to see how the file systems react to less predictable data and to remove the unfair advantage that ZFS has with compression (( yes, I’m going to send the patch to Russell to look at )).

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First Alpha Release of ZFS Using FUSE for Linux with Write Support

Ricardo Correia has announced on his blog about porting Sun Solaris’s ZFS to Linux using FUSE that he has an alpha release with working write support out:

Performance sucks right now, but should improve before 0.4.0 final, when a multi-threaded event loop and kernel caching support are working (both of these should be easy to implement, FUSE provides the kernel caching).

He might be being a little modest about performance, one commenter (Stan) wrote:

Awesome! I compared a zpool with a single file (rather than a partition) compared to ext2 on loopback to a single file. With bonnie++, I was impressed to see the performance of zfs-fuse was only 10-20% slower than ext2.

Stan then went and tried another interesting test:

For fun, check out what happens when you turn compression on and run bonnie++. The bonnie++ test files compress 28x, and the read and write rates quadruple! It’s not a realistic scenario, but interesting to see.

Ricardos list of what should be working in this release is pretty impressive:

  • Creation, modification and destruction of ZFS pools, filesystems, snapshots and clones.
  • Dynamic striping (RAID-0), mirroring (RAID-1), RAID-Z and RAID-Z2.
  • It supports any vdev configuration which is supported by the original Solaris implementation.
  • You can use any block device or file as a vdev (except files stored inside ZFS itself).
  • Compression, checksumming, error detection, self-healing (on redundant pools).
  • Quotas and reservations.

Read his STATUS file to find out what isn’t working too (the main one there I spotted was zfs send and recv).

Caveat: this is an alpha release, so it might eat your data.

Microsoft Details on Vista Protections

For those who would like to see some corroboration of Peter Gutmann’s A Cost Analysis of Windows Vista Content Protection which I posted about previously you can access a document from Microsofts own website called Output Content Protection and Windows Vista which goes into some detail about what you can expect.

In the future, some types of premium content— through its content policy—will specify that a full-resolution analog VGA output is not allowed and that the resolution must be reduced. It is not practical to change the actual scanning rate of the display, particularly because some displays are fixed resolution. But what is important is that the information content of the signal is reduced to the resolution specified by the content owner. Basically, a high-resolution picture needs to be degraded to make it soft and fuzzy.

You may find that if you connect your LCD flat screen via a digital DVI cable it might just stop working.

In contrast, DVI without HDCP is definitely not liked by content owners, because it provides a pristine digital interface that can be captured cleanly. When playing premium content such as HD-DVD and Blu-Ray DVD, PVP-OPM will be required to turn off or constrict the quality of unprotected DVI. As a result, a regular DVI monitor will either get slightly fuzzy or go black, with a polite message explaining that it doesn’t meet security requirements.

Even your analog VGA monitor may get turned off in future.

There have been some successes in getting content owners to make some allowances for this ubiquitous interface. Consumers would certainly be unhappy if it were immediately outlawed; so instead, many content owners are requiring that its resolution be constricted when certain types of premium content are being played. Eventually they may require that analog VGA outputs be turned off completely; but for the moment, it is possible to provide the necessary level of protection by constricting the information content.

It’s not just users who are going to be worse off under this scheme – would you like to be a graphics card manufacturer when Microsoft tell you things like this ?

Content Industry Agreement hardware robustness rules must be interpreted by the graphics hardware manufacturer. Vendors should work to ensure that their implementations will not be revoked for playback of high-level premium content, as the result of a valid complaint from the content owners.

and

It is the responsibility of the graphics chip manufacturer to ensure that their chips are not used to manufacture “hacker friendly” graphics cards or motherboards. If someone does try to manufacture such a card, then the graphics manufacturer should refuse to sell chips to that board manufacturer.

So those are some random restrictions, if you read the whole document you’ll find plenty more to get your blood boiling quite nicely..

Found via a useful comment by Sergio on Bruce Schneier’s blog post about PG’s analysis.

Vacation 1.2.7.0 beta 1 released

Vacation 1.2.7.0 beta1 has been released.

This is a complete rebase from the version of Vacation at Savannah Non-GNU which had been released under the modified BSD license with no advertising clause. This actually means Vacation finally links legally with GDBM (something I don’t believe people previously realised)!

This beta also includes a patch graciously supplied by Roberto Piola that makes Vacation ignore emails that have the SpamAssassin “X-Spam-Status: Yes” header set, indicating that it believes they are spam.

As a beta release from a new codebase you should keep the usual caveats in mind, it may not reply to emails, core dump randomly, blow up, eat your dog or even work properly. We would appreciate reports of all of those instances (well, except maybe for the dog) to the vacation-list kindly hosted at SourceForge.

See the mailing list summary for Vacation to find out how to join the list.

Nadolig Llawen a Blwyddyn Newydd Dda (as they say where I come from). 🙂

Chris

Spam Subject

Todays winner is:

Please do not republish in whole or part without prior written permission.

The irony is that the spammer probably randomly grabbed it from a web page somewhere..