ZFS (was Reliable Firewire drives)

[Dan Shoop]

On Feb 11, 2008, at 6:29 PM, Alex Satrapa wrote:

> On 09/02/2008, at 06:08 , John C. Welch wrote:
>
>> It also points out that contrary to PR, ZFS is not the magic file  
>> system,
>> it's not perfect in form and execution, nor is it the last  
>> filesystem you'll
>> ever need.
>
> The story also points out that in any disaster recovery plan, you  
> have to rehearse the recovery portion of the plan.
>
> That is to say, when making backup copies of file systems as part of  
> a recovery plan, at some point in time someone has to try doing a  
> recovery from the backup copy.  Then you'd have ample warning about  
> file system errors creeping into block-wise copies of your existing  
> file systems.
>
> The story could also be used to point out that block-wise copies of  
> file systems are a  bad idea.  It is obvious that you should do  
> logical copies of the file system (copying file by file), to avoid  
> carrying block-level faults (file system, hardware error, or  
> otherwise) to your precious backup copy.
>
> The story is about poor recovery planning first, bug in file system  
> second.


Neither one should have occurred had only the sysadmins been  
exercising any modicum of due diligence.

I suppose John will say that this is his point, that it's not a magic  
pill, but like in every fairy tale I've ever seen the hero never use  
the old version of the magic spell either nor does he slay the wrong  
dragon or try to win the affections of the princesses aging stepmother.

One might point out that one of ZFS's engineering goals is to assure  
block-wise errors are detected if not fixed, and has a lot of magic  
associated with this; but using an unstable and outdated version (by  
well over a year) and ignoring updates that address significant major  
fixes, is ignoring your job. Your tools can only do their tricks if  
you keep them in working order. I don't expect a broken hammer to  
drive nails and shouldn't complain when its head flies off as I try to  
drive a nail and hits me in the face.

-dhan

------------------------------------------------------------------------
Dan Shoop
Computer Scientist
iWiring / U.S. Technical Services

shoop at iwiring.net
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