* v4 questions, crc's
@ 2004-07-22 21:54 Tom Vier
2006-06-06 19:24 ` Hans Reiser
0 siblings, 1 reply; 6+ messages in thread
From: Tom Vier @ 2004-07-22 21:54 UTC (permalink / raw)
To: reiserfs-list
(resending)
are wandering logs like rcu? unless i'm reading it wrong, it sounds like you
create a copy of the node, but with the updated pointer. you go up the tree,
creating updated parents, and the whole new path is finally committed when
the highest node's pointer is updated, right? how big are nodes in v4? 512
bytes? when updating a tree path, it causes a lot of single sector writes to
different areas (far apart?) but the only dependence is that all the new
updated versions of the nodes must be written before the top node is, right?
does v4 use extents? if not, how are the data blocks finally pointed to?
sun has (or is writing) a new fs i read about recently that has data crc's
with error correction (i guess that's what the new "self healing" buzzword
means - i've heard ibm using it in commercials). i've thought about writing a
v4 plugin. i'm not sure how fine grained to make it. one crc for the whole
file isn't feasable. are blocks variably sized in reiserfs? perhaps each
extent or whatever could be crc'ed, with the crc's stored as metadata (using
whatever method v4 provides for saving variable length metadata).
also, what should i do if a crc is bad? just write to syslog? refuse to
return the data since it might be bad (return an error from read())?
--
Tom Vier <tmv@comcast.net>
DSA Key ID 0x15741ECE
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: v4 questions, crc's
@ 2004-07-22 22:30 David Dabbs
2004-07-23 1:43 ` Tom Vier
0 siblings, 1 reply; 6+ messages in thread
From: David Dabbs @ 2004-07-22 22:30 UTC (permalink / raw)
To: reiserfs-list; +Cc: 'Tom Vier'
Tom,
would you mind forwarding links to the IBM/Sun info you mentioned?
Thanks,
David
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: v4 questions, crc's
2004-07-22 22:30 David Dabbs
@ 2004-07-23 1:43 ` Tom Vier
2004-07-23 14:26 ` Nikita Danilov
2004-07-24 17:26 ` Tom Vier
0 siblings, 2 replies; 6+ messages in thread
From: Tom Vier @ 2004-07-23 1:43 UTC (permalink / raw)
To: David Dabbs; +Cc: reiserfs-list
On Thu, Jul 22, 2004 at 05:30:38PM -0500, David Dabbs wrote:
> would you mind forwarding links to the IBM/Sun info you mentioned?
i'll see if i can find it. i think the sun stuff was on slashdot. as far as
ibm, that was just from their tv commercials. they mention "self healing"
file systems.
--
Tom Vier <tmv@comcast.net>
DSA Key ID 0x15741ECE
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: v4 questions, crc's
2004-07-23 1:43 ` Tom Vier
@ 2004-07-23 14:26 ` Nikita Danilov
2004-07-24 17:26 ` Tom Vier
1 sibling, 0 replies; 6+ messages in thread
From: Nikita Danilov @ 2004-07-23 14:26 UTC (permalink / raw)
To: Tom Vier; +Cc: David Dabbs, reiserfs-list
Tom Vier writes:
> On Thu, Jul 22, 2004 at 05:30:38PM -0500, David Dabbs wrote:
> > would you mind forwarding links to the IBM/Sun info you mentioned?
>
> i'll see if i can find it. i think the sun stuff was on slashdot. as far as
> ibm, that was just from their tv commercials. they mention "self healing"
> file systems.
No serious technical information of Sun ZFS is publicly
available. There is a couple of introductional papers by Valerie
Hensen (http://www.nmt.edu/~val/): http://ohm.hpl.hp.com/self-manage03/Finals/henson-self-tune.pdf
Nikita.
>
> --
> Tom Vier <tmv@comcast.net>
> DSA Key ID 0x15741ECE
>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: v4 questions, crc's
2004-07-23 1:43 ` Tom Vier
2004-07-23 14:26 ` Nikita Danilov
@ 2004-07-24 17:26 ` Tom Vier
1 sibling, 0 replies; 6+ messages in thread
From: Tom Vier @ 2004-07-24 17:26 UTC (permalink / raw)
To: David Dabbs, reiserfs-list
> > would you mind forwarding links to the IBM/Sun info you mentioned?
found it.
http://tinyurl.com/3a3yq
--
Tom Vier <tmv@comcast.net>
DSA Key ID 0x15741ECE
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: v4 questions, crc's
2004-07-22 21:54 v4 questions, crc's Tom Vier
@ 2006-06-06 19:24 ` Hans Reiser
0 siblings, 0 replies; 6+ messages in thread
From: Hans Reiser @ 2006-06-06 19:24 UTC (permalink / raw)
To: Tom Vier; +Cc: reiserfs-list
Tom Vier wrote:
>(resending)
>
>are wandering logs like rcu? unless i'm reading it wrong, it sounds like you
>create a copy of the node, but with the updated pointer. you go up the tree,
>creating updated parents, and the whole new path is finally committed when
>the highest node's pointer is updated, right? how big are nodes in v4? 512
>bytes? when updating a tree path, it causes a lot of single sector writes to
>different areas (far apart?) but the only dependence is that all the new
>updated versions of the nodes must be written before the top node is, right?
>does v4 use extents? if not, how are the data blocks finally pointed to?
>
>sun has (or is writing) a new fs i read about recently that has data crc's
>with error correction (i guess that's what the new "self healing" buzzword
>means - i've heard ibm using it in commercials). i've thought about writing a
>v4 plugin. i'm not sure how fine grained to make it. one crc for the whole
>file isn't feasable. are blocks variably sized in reiserfs? perhaps each
>extent or whatever could be crc'ed, with the crc's stored as metadata (using
>whatever method v4 provides for saving variable length metadata).
>
>
Putting a crc in every node would be easy to code and useful to users.
>also, what should i do if a crc is bad? just write to syslog? refuse to
>return the data since it might be bad (return an error from read())?
>
>
>
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2006-06-06 19:24 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
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2004-07-22 21:54 v4 questions, crc's Tom Vier
2006-06-06 19:24 ` Hans Reiser
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2004-07-22 22:30 David Dabbs
2004-07-23 1:43 ` Tom Vier
2004-07-23 14:26 ` Nikita Danilov
2004-07-24 17:26 ` Tom Vier
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