Bristol Digest, Vol 637, Issue 3

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Today's Topics:

1. Creating/installing VMWare image (Martin Moore)
2. Re: Creating/installing VMWare image (Nick Newbold)
3. Re: Creating/installing VMWare image (Martin Moore)
4. What is with swap? (Andrew)
5. Re: What is with swap? (Max Brooks)
6. Re: What is with swap? (Colin M Strickland)
7. Re: What is with swap? (Alex Butcher (LUG))


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Message: 1
Date: Wed, 16 Mar 2016 17:15:22 +0000
From: Martin Moore <martinm@it-helps.co.uk>
To: Bristol and Bath Linux User Group <bristol@mailman.lug.org.uk>
Subject: [bristol] Creating/installing VMWare image
Message-ID: <D225C367-C25B-46CF-8E42-1125416C888A@it-helps.co.uk>
Content-Type: text/plain; charset="UTF-8"

I?m trying to create a new VM on $dest from running debian server $source

$dest is running a new install of debian. I can create a new VM on $dest but can?t see how to install an image, nor how to create an image.

$dest can ssh into $source using pwd and not keys.

Not can I find anything that makes sense on the mighty Google!

Any tips?


Cheers,

Martin.





------------------------------

Message: 2
Date: Wed, 16 Mar 2016 18:38:46 +0000
From: Nick Newbold <nick@doughnuts.co.uk>
To: Bristol and Bath Linux User Group <bristol@mailman.lug.org.uk>
Subject: Re: [bristol] Creating/installing VMWare image
Message-ID: <78B6FA58-8A40-4BD5-9883-7E480BFB2623@doughnuts.co.uk>
Content-Type: text/plain; charset="Windows-1252"


http://www.vmware.com/uk/products/converter

Sent from my iPhone

> On 16 Mar 2016, at 17:20, Martin Moore <martinm@it-helps.co.uk> wrote:
>
> I?m trying to create a new VM on $dest from running debian server $source
>
> $dest is running a new install of debian. I can create a new VM on $dest but can?t see how to install an image, nor how to create an image.
>
> $dest can ssh into $source using pwd and not keys.
>
> Not can I find anything that makes sense on the mighty Google!
>
> Any tips?
>
>
> Cheers,
>
> Martin.
>
>
>
> _______________________________________________
> Bristol mailing list
> Bristol@mailman.lug.org.uk
> https://mailman.lug.org.uk/mailman/listinfo/bristol



------------------------------

Message: 3
Date: Wed, 16 Mar 2016 18:55:55 +0000
From: Martin Moore <martinm@it-helps.co.uk>
To: Bristol and Bath Linux User Group <bristol@mailman.lug.org.uk>
Subject: Re: [bristol] Creating/installing VMWare image
Message-ID: <B89E6E25-E8C0-49AB-9D7A-689FC5351CEB@it-helps.co.uk>
Content-Type: text/plain; charset="UTF-8"

Cheers - got it though and can?t get it to do what I want. :(

The VMW website and help stuff is really badly put together - I?m surprised they sell anything !




On 16/03/2016, 18:38, "Bristol on behalf of Nick Newbold" <bristol-bounces@mailman.lug.org.uk on behalf of nick@doughnuts.co.uk> wrote:

>
>http://www.vmware.com/uk/products/converter
>
>Sent from my iPhone
>
>> On 16 Mar 2016, at 17:20, Martin Moore <martinm@it-helps.co.uk> wrote:
>>
>> I?m trying to create a new VM on $dest from running debian server $source
>>
>> $dest is running a new install of debian. I can create a new VM on $dest but can?t see how to install an image, nor how to create an image.
>>
>> $dest can ssh into $source using pwd and not keys.
>>
>> Not can I find anything that makes sense on the mighty Google!
>>
>> Any tips?
>>
>>
>> Cheers,
>>
>> Martin.
>>
>>
>>
>> _______________________________________________
>> Bristol mailing list
>> Bristol@mailman.lug.org.uk
>> https://mailman.lug.org.uk/mailman/listinfo/bristol
>
>_______________________________________________
>Bristol mailing list
>Bristol@mailman.lug.org.uk
>https://mailman.lug.org.uk/mailman/listinfo/bristol




------------------------------

Message: 4
Date: Wed, 16 Mar 2016 22:20:44 +0000
From: Andrew <andrewsoltau@gmail.com>
To: Bristol and Bath Linux User Group <bristol@mailman.lug.org.uk>
Subject: [bristol] What is with swap?
Message-ID: <56E9DC3C.9010103@1dtv.com>
Content-Type: text/plain; charset="utf-8"; Format="flowed"

I have what seems to be a swap problem which I do not understand. 8gb of
ram. Running up to date mint mate 17. Main drive is ssd so I put the
swap on a hdd which also holds the main data. Once I have a load of
firefox windows running the system gets incredibly sluggish, and when I
check on the system monitor swap is being used, always a very small
amount. But the usage of the ram never goes over 4.something out of 7.7
gb. I have set swappiness to 0. Is the cure - masses more ram? - cunning
system hack? - use a different browser? - none of the above?
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Message: 5
Date: Wed, 16 Mar 2016 22:29:42 +0000
From: Max Brooks <psykx.out@gmail.com>
To: andrew@1dtv.com, Bristol and Bath Linux User Group
<bristol@mailman.lug.org.uk>
Subject: Re: [bristol] What is with swap?
Message-ID: <BE6CF3D1-F1F2-4C49-A01C-06815AFFAB75@gmail.com>
Content-Type: text/plain; charset=us-ascii

I'd start with getting rid of swap completely, and seeing if that helps. My understanding is that it's not needed any more on modern systems. Especially if it's fetching from swap on the hdd rather than loading from the ssd.

HTH Max

Sent from my iPhone, please excuse any typos.

> On 16 Mar 2016, at 22:20, Andrew <andrewsoltau@gmail.com> wrote:
>
> I have what seems to be a swap problem which I do not understand. 8gb of ram. Running up to date mint mate 17. Main drive is ssd so I put the swap on a hdd which also holds the main data. Once I have a load of firefox windows running the system gets incredibly sluggish, and when I check on the system monitor swap is being used, always a very small amount. But the usage of the ram never goes over 4.something out of 7.7 gb. I have set swappiness to 0. Is the cure - masses more ram? - cunning system hack? - use a different browser? - none of the above?
> _______________________________________________
> Bristol mailing list
> Bristol@mailman.lug.org.uk
> https://mailman.lug.org.uk/mailman/listinfo/bristol



------------------------------

Message: 6
Date: Thu, 17 Mar 2016 06:17:57 +0000
From: Colin M Strickland <cms@beatworm.co.uk>
To: Bristol and Bath Linux User Group <bristol@mailman.lug.org.uk>
Subject: Re: [bristol] What is with swap?
Message-ID: <87d1qt4mnn.fsf@hob.home.beatworm.co.uk>
Content-Type: text/plain


Max Brooks writes:

> I'd start with getting rid of swap completely, and seeing if that helps. My understanding is that it's not needed any more on modern systems. Especially if it's fetching from swap on the hdd rather than loading from the ssd.
>
> HTH Max
>

I keep seeing this 'disable swap completely it's 2016' advice and it
annoys me.

Swap isn't bad. Heavy page swapping is bad, your system shouldn't be
doing this, and it doesn't at all sound like the OP's is. You can look
at this using 'vmstat' - look for the si and so values. Swapping stuff
out ( moving unaccessed memory pages from RAM to disk ) isn't really a
problem, unless you are over-saturated with disk writes ( you're not, or
if you are you have bigger problems that you're already investigating )
swapping stuff in ( moving pages back out of swap into RAM so they can
be used again ) could be more of a problem, especially if it's anything
slightly more than a light tickle of activity. The degree to which it is
a problem depends on how much the delay this introduces into that
particular program's execution impacts your system usefulness. Which is
something of a moveable feast, and probably not noticeable at very low
levels of swap page activity.

The linux vm system is fairly smart. Writes are buffered, pages are
queued to be written to swap in an orderly fashion, and used but
inactive memory pages are identified by kernel access metrics and some
heuristics, In a well behaved system, without memory pressure, the
small, fairly static amount of pages pushed to swap represent memory
that isn't being used for useful work - typically programs used some
portion of this at some stage of their execution and haven't bothered
with it for some time - the classical explanation is data pages that are
only used in application initialisation - but really the what doesn't
matter, the important point is that the kernel is pretty good at
identifying this low level waste, and helpfully reclaiming the RAM for
it's own use. You *always* want as much free physical RAM as possible (
as in physical memory pages that aren't being used by applications for
data ), because it's super-useful as IO buffering - the kernel
aggressively uses system memory as disk cache - In this way, pages
pushed out to swap are actually helping to make your system run more
quickly, not slowing it down.

Programs with low level memory leaking are well served by swap - and
they've all got them, it's one of the most commonly occuring UNIX/C
programming bugs - rather than rob your system of useful memory for
work, these allocated then never freed resources will just end up
squatting on a few disk pages you probably don't care about.

Swap can save your ass! A sudden surge in memory usage by a process
doing something unexpected ( like reading in a much larger data file
than you expected, or a buggy loop allocating memory ), you have a
stopgap of RAM - your system will suffer some slowdown, and recover, or
give you the chance to identify the problem process and deal with it.

Without recourse to swap, memory pressure gets you a couple of
results. Either the system OOM triggers process killers, which try to
use heuristics to identify programs that should be terminated to recover
RAM ( quite annoying that turns out to be the large strategy game you
just tabbed away from playing, or your critical database server, or
perhaps your desktop session manager ), *OR* you crash your computer
with an OOM panic/halt losing everything.

The cost is so low - typically you have much more disk space than RAM
available to you, so trading a few GB of disk away in return for a
guarantee of more system stability and better runtime performance is
almost always going to be a good investment.

As ever, avoid reflexive adherence to dogma, including all the advice in
this email. If you're reading this and thinking 'all this sounds very
interesting cms, but you're not really describing my system setup or
behaviour', then by all means figure out the right path for
yourself. There are a lot of tuneable variables for VM ( of course there
are, this is linux, right? ), and I will note that the more your system
deviates from 'average system', the more the default knob settings the
kernel uses to inform its ideas about memory pressure / swap heuristics
will probably require tuning. Of course if you're using a distribution
that's well matched to your unusual hardware, some other kind gentlefolk
will probably have already done this for you. I've had the luck of
working on some unusually specified hardware from time to time over the
years, and on occasion the linux VM subsystems have gifted me a few
surprises. Set up well though they've always been a gift that have
offered me useful paths to more optimised system performance. I like
swap, it's a useful tool to have in the box. And yes, sometimes a useful
tool to leave on the bench, once you understand what and why.

--
Regards,
Colin M . Strickland, cms, 'that guy'



------------------------------

Message: 7
Date: Thu, 17 Mar 2016 08:33:45 +0000
From: "Alex Butcher (LUG)" <lug@assursys.co.uk>
To: andrew@1dtv.com, Bristol and Bath Linux User Group
<bristol@mailman.lug.org.uk>
Subject: Re: [bristol] What is with swap?
Message-ID: <CAC10725-5794-42EF-863A-F410CC6D9B8E@assursys.co.uk>
Content-Type: text/plain; charset="utf-8"

On which drive is your /home filesystem located? And /tmp?

On 16 March 2016 22:20:44 GMT+00:00, Andrew <andrewsoltau@gmail.com> wrote:
>I have what seems to be a swap problem which I do not understand. 8gb
>of
>ram. Running up to date mint mate 17. Main drive is ssd so I put the
>swap on a hdd which also holds the main data. Once I have a load of
>firefox windows running the system gets incredibly sluggish, and when I
>
>check on the system monitor swap is being used, always a very small
>amount. But the usage of the ram never goes over 4.something out of 7.7
>
>gb. I have set swappiness to 0. Is the cure - masses more ram? -
>cunning
>system hack? - use a different browser? - none of the above?
>
>
>------------------------------------------------------------------------
>
>_______________________________________________
>Bristol mailing list
>Bristol@mailman.lug.org.uk
>https://mailman.lug.org.uk/mailman/listinfo/bristol

--
Sent from my Android phone with K-9 Mail. Please excuse my brevity.
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End of Bristol Digest, Vol 637, Issue 3
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