swap_pager indefinite wait buffer - question - SOLVED

[Matthew Dillon]

Ultimately the most robust storage solution is going to be a permanent,
direct SATA-connected SSD, either 2.5" or a M.2 form factor depending on
the hardware.  It's possible to make it very lean, the system can easily be
installed in a small ~64GB SSD.  With a USB stick, definitely not (the
stick will wear out very quickly).

As long as one is not writing gigabytes to the SSD every day, it will last
forever.  Even though HDDs (spinning rust) might be cheaper, they they will
die relatively quickly in a rough environment and require replacement (or
the equipment will wind up just being unusable and junked when they fail).

Another advantage of a small SSD is that swap space can be configured on
it, which means the system can page very efficiently to/from it and be able
to make far better use of the 1GB of ram.  And with a SSD, paging from swap
is very fast so users won't notice the lag as much if running a big program.

USB-attached hard drives are not going to be as reliable as direct SATA
connected drives for several reasons, the main one being that the system
can't survive a disconnect/reconnect if root happens to be on the
usb-connected drive.  Performance is also going to suffer significantly
with USB-attached drives verses direct SATA-attached drives.  SATA attached
drives will use the AHCI driver and can handle high concurrent loads even
in lean configurations (paging to/from swap can create high concurrent
loads).

-Matt

On Fri, Dec 26, 2014 at 8:12 PM, Matthew Dillon <dillon at backplane.com>
wrote:

> That's an excellent use of a free OS.  I was in Tanzania at the beginning
> of the year on vacation.  You can do a lot with 1GB and a lean UI.  All the
> BSDs should do quite well in that configuration.
>
> -Matt
>
> On Fri, Dec 26, 2014 at 4:05 AM, PeerCorps Trust Fund <
> ipc at peercorpstrust.org> wrote:
>
>> It certainly is, although the machines are actually running stock FreeBSD
>> 10.1.
>>
>> PC-BSD was an option in the beginning, but because these were older
>> computers it was easier to build a low-resource install enabling only basic
>> services such as NFS rather than trying to pare down a PC-BSD install to
>> suit the needs of the project (which is a basic KDE-based workstation).
>>
>> Most of those desktops had only one gigabyte of RAM ad PC-BSD uses a lot
>> of resources. We learned a lot in the process and will be implementing
>> modified libraries in the coming year using donated computer equipment.
>>
>> I think many underestimate the enormous value that such projects have in
>> these communities. Just having access to books and educational material is
>> tremendously beneficial from a development perspective.
>>
>> On 12/26/2014 01:12 PM, Carsten Mattner wrote:
>> > On Fri, Dec 26, 2014 at 12:43 AM, PeerCorps Trust Fund
>> > <ipc at peercorpstrust.org> wrote:
>> >> Indeed in Tanzania :) we have a couple of technology initiatives
>> taking place at the
>> >> moment and *BSD is at the center in many ways. The delivery of
>> educational
>> >> materials and books to resource-limited communities is an important
>> aim of
>> >> these initiatives.
>> >>
>> >> We actually used FreeBSD in our first effort, but want to experiment
>> with some
>> >> of the capabilities of DragonflyBSD and HAMMER in the next one. In our
>> >> estimation we can possibly stretch our hardware and funds a bit
>> further with
>> >> DragonflyBSD/HAMMER owing to its low resource requirements.
>> >
>> > Ah nice. Is it the same project we heard recently of with photos of a
>> library
>> > room running PCBSD machines with a video and document library?
>> >
>> >
>> >> On 12/25/2014 11:20 PM, Carsten Mattner wrote:
>> >>> On Thu, Dec 25, 2014 at 7:08 PM, PeerCorps Trust Fund
>> >>> <ipc at peercorpstrust.org> wrote:
>> >>>> I just wanted to take the opportunity update a previous post that I
>> made to the
>> >>>> list concerning a swap_pager concern. It isn't an issue at all but
>> the fault of my
>> >>>> own ignorance and hardware limits.
>> >>>>
>> >>>> The external drive in question was simply not pulling enough power
>> from the
>> >>>> USB port of the laptop. This was likely resulting in a stalled drive
>> when anything
>> >>>> substantial was being copied to it.
>> >>>>
>> >>>> This has since been solved by connecting the drive first to an
>> externally powered
>> >>>> USB hub. So, if there is anyone else out there having a similar
>> issue, trying this
>> >>>> seems to do the trick. Alternatively, just use a drive that is
>> powered externally.
>> >>>>
>> >>>> Everything works beautifully now and this low cost experiment for a
>> simple file
>> >>>> server will find a home in a school classroom next year.
>> >>>
>> >>> In Tanzania?
>> >>>
>> >>> FreeBSD had a writeup about a set of PCBSD machines installed in
>> Nigeria IIRC.
>> >>>
>> >>> A blog post or other writeup to link on dragonflybsd.org would
>> surely be nice.
>> >>>
>> >>
>>
>> --
>> Michael L. Wilson
>> International Project Coordinator
>> PeerCorps Trust Fund - Tanzania
>>
>>
>>
>
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