Re: [PLUG] [plug-announce] TOMORROW - Tue, Apr 19, 2016: PLUG North - "Linux Containers" by Jason Plum and Rich Freeman (*6:30 pm* at CoreDial in Blue Bell)

["Keith C. Perry" <kperry@daotechnologies.com>]

The redundancy in the in redundancy bits for the error correction.  See section 4.1 of this paper:

http://pages.cs.wisc.edu/~vshree/xfs.pdf

Also, for what its worth, some other discussion generally about how we ensure data reaches the disk.  Basically a discussion on the problem caching and how barrier mode is necessary for reliability (XFS has that turned on by default).  This is an example of a hardware issue that has nothing to do specifically with file system you are running.

https://lwn.net/Articles/457667/

Finally, an article from January 2012 discussing why XFS will probably become the default file system over EXT4 and why in the future it will probably be BTRFS if all the issues can be worked out.  I only include it to illustrate how people get wrapped in the religious fight while ignoring the fact that there is a lot that goes into the process so saying "my god is more reliable that your god" gets a bit too far into the weeds.  Funny how that always happens.  :D

http://lwn.net/Articles/476263/


~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ 
Keith C. Perry, MS E.E. 
Owner, DAO Technologies LLC 
(O) +1.215.525.4165 x2033 
(M) +1.215.432.5167 
www.daotechnologies.com

----- Original Message -----
From: "Rich Freeman" <r-plug@thefreemanclan.net>
To: "Philadelphia Linux User's Group Discussion List" <plug@lists.phillylinux.org>
Sent: Monday, April 25, 2016 8:37:42 PM
Subject: Re: [PLUG] [plug-announce] TOMORROW - Tue, Apr 19, 2016: PLUG North - "Linux Containers" by Jason Plum and Rich Freeman (*6:30 pm* at CoreDial in Blue Bell)

On Mon, Apr 25, 2016 at 8:03 PM, Keith C. Perry
<kperry@daotechnologies.com> wrote:
> I wouldn't say rsync is 100% actually.  I've had problems with it since it doesn't know is everything has been written to disk.

It is only 100% with the --checksum option, which requires both sides
of the rsync to read every file that has matching metadata.  Almost
nobody uses this option as a result as it is A LOT slower.  zfs and
btrfs can reliably detect any modification to a file (whether it be in
the data or the inode) without having to read anything but the
metadata, and using a btree search it doesn't even have to check most
of the metadata.

-- 
Rich
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