From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tom Vier Subject: v4 questions, crc's Date: Thu, 22 Jul 2004 17:54:09 -0400 Message-ID: <20040722215409.GA12240@zero> Reply-To: Tom Vier Mime-Version: 1.0 Return-path: list-help: list-unsubscribe: list-post: Errors-To: flx@namesys.com Content-Disposition: inline List-Id: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: reiserfs-list@namesys.com (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 DSA Key ID 0x15741ECE