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From: Arthur Krewat <krewat@kilonet.net>
To: Larry McVoy <lm@mcvoy.com>
Cc: tuhs@minnie.tuhs.org
Subject: Re: [TUHS] If not Linux, then what?
Date: Mon, 26 Aug 2019 20:59:02 -0400
Message-ID: <312b39a1-2944-100f-55e0-fc65b504d43d@kilonet.net> (raw)
In-Reply-To: <20190827003013.GS13570@mcvoy.com>

On 8/26/2019 8:30 PM, Larry McVoy wrote:
>
> I really don't understand the love for ZFS.  I hired Bonwick and I
> hired Moore, I had high expectations but they were all dashed when I
> realized ZFS doesn't use the page cache.  That's so crazy busted I lost
> all interest in ZFS.  ZFS took us back to HP-UX mmap semantics.
>

At the risk of going off-topic:

 From a system-administration standpoint, and data-integrity standpoint, 
ZFS was a huge step forward. In my humble opinion ;)

Besides the obvious (to me) benefits of adding mount points, adjusting 
volume sizes, and all the other things that ZFS does, I have yet to find 
any mainstream filesystem (if you can call ZFS "just" a filesystem) that 
guarantees data integrity. I have an office server, that contains a lot 
of source code and archived data that I depend on religiously. I do 
copious backups to LTO tapes as well as an off-site Amazon EC2 instance.

Within the recent past few years, I had an issue with a Dell MD Raid 
array where ZFS was complaining about checksum errors on a certain disk. 
Data was being corrupted on the fly. It seems that the writes were being 
corrupted, not reads. Thankfully, it was on a RAIDZ2 volume, where it 
could correct the corruption. The corruption in question was on files 
that are dated back to the early 90's.

Stopping bit-rot in it's tracks, ZFS has done me well.

As for what mmap() doesn't do right, I started using memory mapped files 
back in the early 80s on VMS on a VAX-11/780 when I and a colleague were 
converting a database from TOPS-10 to VMS. Perhaps I am misunderstanding 
your dislike for mmap() but please, enlighten me. It was my 
understanding at the time that it was akin to swapping/virtual-memory 
using an MMU. The difference was that instead of using the main paging 
area, the kernel would use an actual file.  Why would mmap() be a bad 
thing, when it's hooked into the kernel, and possibly hardware, at such 
a low point?

art k.




  parent reply index

Thread overview: 96+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-26 23:13 Arthur Krewat
2019-08-26 23:27 ` Warner Losh
2019-08-26 23:37   ` Larry McVoy
2019-08-26 23:56   ` William Pechter
2019-08-27  0:19     ` Arthur Krewat
2019-08-27  0:30       ` Larry McVoy
2019-08-27  0:58         ` Rob Pike
2019-08-27  1:06           ` Clem Cole
2019-08-27  2:53           ` Larry McVoy
2019-08-27  9:47             ` Rob Pike
2019-08-27  7:47           ` arnold
2019-08-27 16:05           ` [TUHS] Running v10 Angelo Papenhoff
2019-08-27 16:27             ` Henry Bent
2019-08-28  4:22               ` Jason Stevens
2019-08-28  7:34                 ` Angelo Papenhoff
2019-08-28 16:46                   ` Henry Bent
2019-08-27  0:59         ` Arthur Krewat [this message]
2019-08-27  1:26           ` [TUHS] If not Linux, then what? Dan Cross
2019-08-27  2:45             ` Larry McVoy
2019-08-27  3:14               ` Arthur Krewat
2019-08-27 14:55                 ` Larry McVoy
2019-08-27 22:30                   ` George Michaelson
2019-08-27 22:40                     ` Larry McVoy
2019-08-27 22:46                       ` George Michaelson
2019-08-27 22:59                         ` [TUHS] [SPAM] " Larry McVoy
2019-08-27 23:10                           ` [TUHS] " Clem Cole
2019-08-28  0:07                             ` George Michaelson
2019-08-28  3:22                           ` [TUHS] [SPAM] " Rob Pike
2019-08-28  3:25                             ` Rob Pike
2019-08-28  4:05                             ` Larry McVoy
2019-08-28 13:52                               ` Clem Cole
2019-08-28 14:31                                 ` [TUHS] " Larry McVoy
2019-08-28 14:57                                   ` Clem Cole
2019-08-28  6:19                         ` Wesley Parish
2019-08-28  6:30                           ` Peter Jeremy
2019-08-28 11:05                             ` Jason Stevens
2019-08-28 11:11                               ` Arrigo Triulzi
2019-08-28 14:04                               ` Clem Cole
2019-08-28 16:34                                 ` Henry Bent
2019-08-28 17:32                                   ` Larry McVoy
2019-08-28 17:51                                     ` Jon Forrest
2019-08-28 18:56                                     ` Clem Cole
2019-08-28 20:23                                       ` Arrigo Triulzi
2019-08-29  3:24                                       ` Lawrence Stewart
2019-08-29 10:55                                         ` Tony Finch
2019-08-28 13:57                             ` Clem Cole
2019-08-28 12:46                           ` Warner Losh
2019-08-27 23:16                       ` Bakul Shah
2019-08-27 23:33                         ` Larry McVoy
2019-08-28  0:21                           ` Bakul Shah
2019-08-28  1:21                             ` Arthur Krewat
2019-08-28  1:46                               ` Larry McVoy
2019-08-27  0:48   ` Clem Cole
2019-08-27  1:25     ` Gregg Levine
2019-08-27  2:16   ` Theodore Y. Ts'o
2019-08-27  2:39     ` Larry McVoy
2019-08-27  5:54       ` Adam Thornton
2019-08-27  6:05         ` Gregg Levine
2019-08-27  1:17 ` Dan Cross
2019-08-28  3:53 ` Charles H. Sauer
2019-08-28  4:30 ` Jason Stevens
2019-08-28  9:36 ` Angus Robinson
2019-08-28  9:50   ` Michael Kjörling
2019-08-28 10:48     ` arnold
2019-08-28 14:10   ` Earl Baugh
2019-08-28 14:55     ` Clem Cole
2019-08-28 14:22   ` Charles H Sauer
2019-08-28 15:00     ` Steve Nickolas
2019-08-28 15:37       ` Richard Salz
2019-08-28 19:54         ` Peter Jeremy
2019-08-28 20:05           ` Christopher Browne
2019-08-28 20:07 ` Christopher Browne
2019-08-28 20:27   ` Adam Thornton
2019-08-28 20:56     ` William Pechter
2019-08-28 22:24       ` Clem cole
2019-08-28 22:27     ` William Pechter
2019-08-28 22:53       ` Arthur Krewat
2019-08-29 18:40       ` Nemo Nusquam
2019-08-29 19:18         ` Steffen Nurpmeso
2019-08-28 22:28     ` Clem cole
2019-08-28 22:48       ` Adam Thornton
2019-08-28 23:01         ` William Pechter
2019-08-28 23:09           ` Adam Thornton
2019-08-29  6:37           ` Wesley Parish
2019-08-28 23:04       ` Gregg Levine
2019-08-29 11:12     ` Tony Finch
2019-08-28 23:19   ` Theodore Y. Ts'o
2019-08-29 13:31     ` A. P. Garcia
2019-08-29 13:55       ` Arthur Krewat
2019-08-29 15:54         ` Thomas Paulsen
2019-08-29 19:19           ` Steffen Nurpmeso
2019-08-31  1:35             ` Dave Horsfall
2019-08-31 15:14               ` Steffen Nurpmeso
2019-08-31 16:58     ` Christopher Browne
2019-08-31 21:20       ` Theodore Y. Ts'o
2019-08-28 21:02 ` Thomas Paulsen

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