Re: freshly installed SW not found

From	William Unruh <unruh@invalid.ca>
Newsgroups	alt.os.linux
Subject	Re: freshly installed SW not found
Date	2019-03-02 16:29 +0000
Organization	A noiseless patient Spider
Message-ID	<q5eb10$114$1@dont-email.me> (permalink)
References	(6 earlier) <op.zxznlbyza3w0dxdave@hodgins.homeip.net> <q5cfp2$rfr$1@dont-email.me> <op.zxzz16nca3w0dxdave@hodgins.homeip.net> <q5cud4$s7b$1@dont-email.me> <q5dh9n$em7$1@dont-email.me>

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On 2019-03-02, Paul <nospam@needed.invalid> wrote:
> William Unruh wrote:
>> On 2019-03-02, David W. Hodgins <dwhodgins@nomail.afraid.org> wrote:
>>> On Fri, 01 Mar 2019 18:38:10 -0500, William Unruh <unruh@invalid.ca> wrote:
>>>
>>>> On 2019-03-01, David W. Hodgins <dwhodgins@nomail.afraid.org> wrote:
>>>>> Then use freedups to remove one copy of the compressed copies of the
>>>>> file, when it's exactly the same as the previously created compressed
>>>>> copy of the file.
>>>> This is really slow. You would have to use MD5 hash to decide if the two
>>>> compressed copies are the same, which is slow (rsync by default uses the
>>>> date and time of the file to decide if they are the same.)
>>>> If you have thousands of hard links ( which Soviet implied he had) that
>>>> will take forever.
>>> The first time it's run, yes. It stores the md5 hash values in a file in
>>> the /root directory. After that it only needs to calculate them for new
>>> or changed files.
>> 
>> But the only way you know if the file is changed is to run the md5hash.
>> That is not fast. Youhave to run the hash on every file every time. 
>
> This in fact, loads the system read cache. If the MD5sum is
> changed from previously, now when you want to copy the file,
> the "source" file is already present in memory and ready to be
> copied somewhere. The "I/O effort" isn't wasted.

It it is small it may be in memory. But MD5 is a serial hash. You start
at the beginning and go, byte by byte to the end. There is no need to
save the file and certainly md5sum does not.


>
> MD5 is decently fast in my book. For HDD systems, it could well
> be the read-rate of the HDD that limits performance. (A quick
> bench of md5deep64 here yields about 450MB/sec. Almost a match
> for a SATAIII SSD. Someone with a 5GHz turbo processor could
> easily beat my bench (there is one processor that will turbo
> on two cores at 5GHz, to make this happen).)

Parallelism does nothing, AFAIK for MD5. You start at the beginning and
go to the end, and you cannot do anything with any piece of data  that
helps until you get to it, as I understand.

>
>     Paul

Thread

freshly installed SW not found Soviet_Mario <SovietMario@CCCP.MIR> - 2019-02-26 19:47 +0100
  Re: freshly installed SW not found "J.O. Aho" <user@example.net> - 2019-02-26 20:28 +0100
    Re: freshly installed SW not found Soviet_Mario <SovietMario@CCCP.MIR> - 2019-02-26 21:51 +0100
      Re: freshly installed SW not found William Unruh <unruh@invalid.ca> - 2019-02-26 21:46 +0000
        Re: freshly installed SW not found Soviet_Mario <SovietMario@CCCP.MIR> - 2019-02-27 12:52 +0100
          Re: freshly installed SW not found Aragorn <thorongil@telenet.be> - 2019-02-27 12:44 +0000
            Re: freshly installed SW not found Dan Purgert <dan@djph.net> - 2019-02-27 13:27 +0000
            Re: freshly installed SW not found Richard Kettlewell <invalid@invalid.invalid> - 2019-02-27 15:16 +0000
            Re: freshly installed SW not found Soviet_Mario <SovietMario@CCCP.MIR> - 2019-02-27 16:59 +0100
              Re: freshly installed SW not found Dan Purgert <dan@djph.net> - 2019-02-27 16:02 +0000
                Re: freshly installed SW not found Soviet_Mario <SovietMario@CCCP.MIR> - 2019-02-27 20:46 +0100
                Re: freshly installed SW not found William Unruh <unruh@invalid.ca> - 2019-02-27 20:18 +0000
                Re: freshly installed SW not found Soviet_Mario <SovietMario@CCCP.MIR> - 2019-02-28 12:47 +0100
                Re: freshly installed SW not found William Unruh <unruh@invalid.ca> - 2019-02-28 18:32 +0000
                Re: freshly installed SW not found Soviet_Mario <SovietMario@CCCP.MIR> - 2019-03-01 01:14 +0100
                Re: freshly installed SW not found "Carlos E.R." <robin_listas@es.invalid> - 2019-03-01 01:54 +0100
                Re: freshly installed SW not found Jasen Betts <jasen@xnet.co.nz> - 2019-03-01 03:09 +0000
                Re: freshly installed SW not found Aragorn <thorongil@telenet.be> - 2019-02-27 20:21 +0000
                Re: freshly installed SW not found William Unruh <unruh@invalid.ca> - 2019-02-27 23:02 +0000
                Re: freshly installed SW not found Richard Kettlewell <invalid@invalid.invalid> - 2019-02-27 23:24 +0000
                Re: freshly installed SW not found Jasen Betts <jasen@xnet.co.nz> - 2019-02-28 04:46 +0000
                Re: freshly installed SW not found Dan Purgert <dan@djph.net> - 2019-02-28 10:59 +0000
                Re: freshly installed SW not found Soviet_Mario <SovietMario@CCCP.MIR> - 2019-02-28 18:51 +0100
                Re: freshly installed SW not found William Unruh <unruh@invalid.ca> - 2019-02-28 18:24 +0000
                Re: freshly installed SW not found Dan Purgert <dan@djph.net> - 2019-03-01 13:49 +0000
                Re: freshly installed SW not found "Carlos E.R." <robin_listas@es.invalid> - 2019-03-01 18:22 +0100
                Re: freshly installed SW not found Aragorn <thorongil@telenet.be> - 2019-03-01 19:06 +0000
                Re: freshly installed SW not found Soviet_Mario <SovietMario@CCCP.MIR> - 2019-03-03 01:08 +0100
                Re: freshly installed SW not found Aragorn <thorongil@telenet.be> - 2019-03-03 00:14 +0000
                Re: freshly installed SW not found Dan Purgert <dan@djph.net> - 2019-03-03 13:00 +0000
                Re: freshly installed SW not found Dan Purgert <dan@djph.net> - 2019-03-03 12:46 +0000
                Re: freshly installed SW not found William Unruh <unruh@invalid.ca> - 2019-02-28 18:15 +0000
              Re: freshly installed SW not found William Unruh <unruh@invalid.ca> - 2019-02-27 16:38 +0000
                Re: freshly installed SW not found Soviet_Mario <SovietMario@CCCP.MIR> - 2019-02-27 20:51 +0100
              Re: freshly installed SW not found Jasen Betts <jasen@xnet.co.nz> - 2019-02-28 04:39 +0000
        Re: freshly installed SW not found "Carlos E.R." <robin_listas@es.invalid> - 2019-02-27 14:30 +0100
      Re: freshly installed SW not found "J.O. Aho" <user@example.net> - 2019-02-27 07:05 +0100
      Re: freshly installed SW not found "Carlos E.R." <robin_listas@es.invalid> - 2019-02-27 14:29 +0100
        Re: freshly installed SW not found Paul <nospam@needed.invalid> - 2019-02-27 08:50 -0500
          Re: freshly installed SW not found "Carlos E.R." <robin_listas@es.invalid> - 2019-02-28 00:05 +0100
        Re: freshly installed SW not found Soviet_Mario <SovietMario@CCCP.MIR> - 2019-02-27 16:56 +0100
        Re: freshly installed SW not found Chris <ithinkiam@gmail.com> - 2019-03-01 14:58 +0000
      Re: freshly installed SW not found Chris <ithinkiam@gmail.com> - 2019-03-01 15:04 +0000
        Re: freshly installed SW not found "David W. Hodgins" <dwhodgins@nomail.afraid.org> - 2019-03-01 10:50 -0500
          Re: freshly installed SW not found William Unruh <unruh@invalid.ca> - 2019-03-01 18:40 +0000
            Re: freshly installed SW not found "David W. Hodgins" <dwhodgins@nomail.afraid.org> - 2019-03-01 14:40 -0500
              Re: freshly installed SW not found William Unruh <unruh@invalid.ca> - 2019-03-01 23:38 +0000
                Re: freshly installed SW not found "David W. Hodgins" <dwhodgins@nomail.afraid.org> - 2019-03-01 19:09 -0500
                Re: freshly installed SW not found William Unruh <unruh@invalid.ca> - 2019-03-02 03:47 +0000
                Re: freshly installed SW not found "David W. Hodgins" <dwhodgins@nomail.afraid.org> - 2019-03-01 22:55 -0500
                Re: freshly installed SW not found William Unruh <unruh@invalid.ca> - 2019-03-02 07:08 +0000
                Re: freshly installed SW not found "Carlos E.R." <robin_listas@es.invalid> - 2019-03-02 11:27 +0100
                Re: freshly installed SW not found Paul <nospam@needed.invalid> - 2019-03-02 04:10 -0500
                Re: freshly installed SW not found William Unruh <unruh@invalid.ca> - 2019-03-02 16:29 +0000
                Re: freshly installed SW not found Paul <nospam@needed.invalid> - 2019-03-02 11:54 -0500
                Re: freshly installed SW not found "Carlos E.R." <robin_listas@es.invalid> - 2019-03-02 11:24 +0100
                Re: freshly installed SW not found Jasen Betts <jasen@xnet.co.nz> - 2019-03-02 00:28 +0000
                Re: freshly installed SW not found "Carlos E.R." <robin_listas@es.invalid> - 2019-03-02 11:31 +0100
                Re: freshly installed SW not found Aragorn <thorongil@telenet.be> - 2019-03-02 11:31 +0000
                Re: freshly installed SW not found Melzzzzz <Melzzzzz@zzzzz.com> - 2019-03-02 11:34 +0000
                Re: freshly installed SW not found Aragorn <thorongil@telenet.be> - 2019-03-02 11:48 +0000
                Re: freshly installed SW not found Melzzzzz <Melzzzzz@zzzzz.com> - 2019-03-02 12:15 +0000
                Re: freshly installed SW not found "Carlos E.R." <robin_listas@es.invalid> - 2019-03-02 23:15 +0100
                Re: freshly installed SW not found Chris Elvidge <chris@mshome.net> - 2019-03-03 00:33 +0000
                Re: freshly installed SW not found Soviet_Mario <SovietMario@CCCP.MIR> - 2019-03-03 01:38 +0100
                Compressed filesystems [Was: Re: freshly installed SW not found] "Carlos E.R." <robin_listas@es.invalid> - 2019-03-03 13:11 +0100
                Re: Compressed filesystems [Was: Re: freshly installed SW not found] Soviet_Mario <SovietMario@CCCP.MIR> - 2019-03-03 19:49 +0100
                Re: Compressed filesystems [Was: Re: freshly installed SW not found] "Carlos E.R." <robin_listas@es.invalid> - 2019-03-03 21:17 +0100
                Re: freshly installed SW not found Dan Purgert <dan@djph.net> - 2019-03-03 12:49 +0000
                Re: freshly installed SW not found Melzzzzz <Melzzzzz@zzzzz.com> - 2019-03-03 12:35 +0000
            Re: freshly installed SW not found "Carlos E.R." <robin_listas@es.invalid> - 2019-03-02 11:22 +0100
  Re: freshly installed SW not found Wildman <best_lay@yahoo.com> - 2019-02-26 13:31 -0600
    Re: freshly installed SW not found Wildman <best_lay@yahoo.com> - 2019-02-26 15:42 -0600
      Re: freshly installed SW not found William Unruh <unruh@invalid.ca> - 2019-02-26 21:51 +0000
  Re: freshly installed SW not found "David W. Hodgins" <dwhodgins@nomail.afraid.org> - 2019-02-26 14:36 -0500
    Re: freshly installed SW not found Soviet_Mario <SovietMario@CCCP.MIR> - 2019-02-26 21:58 +0100
      Re: freshly installed SW not found William Unruh <unruh@invalid.ca> - 2019-02-26 21:49 +0000
        Re: freshly installed SW not found Soviet_Mario <SovietMario@CCCP.MIR> - 2019-02-27 12:54 +0100
  Re: freshly installed SW not found William Unruh <unruh@invalid.ca> - 2019-02-26 19:51 +0000

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