Less known Solaris Features: CacheFS - Part 7: The future of CacheFS

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Less known Solaris Features: CacheFS - Part 7: The future of CacheFS

Monday, August 18. 2008

CacheFS is one of this hidden gems in Solaris, it´s even that hidden, that it´s in sustaining mode since 1999. That means, that only bugfixes are made for this features but no new features found their way into this component since that day. In the recent days there was some discussion about the declaration of the End-of-Feature status for CacheFS which will lead to the announcement of the removal of CacheFS. After a few days of discussion the ARC decided in favour of the removal.

There are several problems with CacheFS (for example it´s incompatibility with NFSv4) that mandates a major redesign of CacheFS, but CacheFS solves customer problems today. Thus i´m strongly disagree with the idea of removing a part of Solaris as long there is no equivalent feature (in this case: as long there isn´t a new boot-persistent caching for NFS available in Solaris).

As i want to place a RFE to add an equivalent feature it would be very helpful to get some information from you:

Do you already use CacheFS?
In the case you use CacheFS at the moment ...

Is a removal of CacheFS a problem for you?
Would the removal hurt the deployment of Solaris at your site
Would you use an equivalent feature?

In the case you didn´t used CacheFS so far ...

Is CacheFS a desirable feature for you after reading the tutorial?
Is CacheFS a feature that would help the deployment and adoption of Solaris at your site?

Please answer this questions by commenting this article. Thank you in advance!

Posted by Joerg Moellenkamp in English, Solaris at 18:24 | Comments (9) | Trackback (1)

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Less known Solaris Features: CacheFS
Yet another tutorial finalized - this time about one of the really hidden features of Solaris - CacheFS. CacheFS is something similar to a caching proxy. But this proxy don´t cache web page, it caches files from another filesystem. Introduction Theo

Weblog: c0t0d0s0.org
Tracked: Aug 18, 19:58

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We used to use CacheFS at a previous company. It is possible that it is still in use today.

#1 Shawn Ferry on 2008-08-19 01:57

CacheFS sound like a very nifty feature that could solve some of my problems.
Can CacheFS be used as a kind of failure resistent filesystem?
Like I have a webserver with NFS but the NFS server dies for some reason.
If the backend dies, is the CacheFS still be useable, or does it depend on a working backend?
I can image some situations where such a feature would make the difference – I would hate to see such a feature be removed.
I think I need to talk to my Sunnie

#2 Joern K. on 2008-08-19 09:44

There is (was ... i used it with Solaris 9 the last time) an undocumented feature called "disconnected mode" in Solaris. In the case a backfs mount gets dysfunctional, the requests are answered from the cache.

#2.1 Joerg+M. (Homepage) on 2008-08-19 10:26

What does undocumented mean?
Is it a supported feature, or a beta feature or is it not supported at all?

#2.1.1 Joern+K. on 2008-08-19 12:06

It´s not in beta, it´s in the code for year, i will look after the support status of this feature.

At the moment, it´s just not documented how to activate it ...

#2.1.1.1 Joerg+M. (Homepage) on 2008-08-19 13:06

CacheFS is a wonderful concept, however the implementation is so bad that it should be retired. Performance is awful, even in workloads where it should be fast. If there is desire for this sort of functionality, it would be best to learn from past mistakes (and successes like Windows CSC and DFSR) and start from scratch.

#3 Doc on 2008-08-19 10:15

We've had mixed results with cachefs--it didn't always behave well if a file was always changing.

If a new cache feature was added, i'd be curious if code was taken from the Java System Web Proxy Server product as it sounds like a good bit of work was done for intelligent hierarchical caches.

#4 sleepyweasel on 2008-09-19 17:51

CacheFS is very useful, I work at a tier-2 ISP and we find uses for it in many places. Removing it because it is old and could be better is fair enough, but why not write an equivalent that works with NFSv4 and improve it while your at it?

As a working example, we use it to reduce load on back end storage systems (for data that very rarely changes but is accessed a LOT - say every time an email is received by any of our customers), therefore massively extending the lifetime of very expensive storage hardware like Netapp filers.

#5 Josh on 2008-09-26 11:57

I read this in disbelief. So many good things have been discarded ( webNFS is one), not only we should continue to have cachefs, we
should standardize it so that Linux and OS x can use it.

#6 C. Lin on 2008-11-07 04:50

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