[GLLUG] Low-power Home Server

Sun Jul 29 14:25:17 EDT 2012

For ext2... for low memory device, you can't afford to use 4k block sizes.
Try upping that to 32k and I expect your memory use will drop by nearly a
factor of 8.  Of course, you will have more far wasted space.
On Jul 29, 2012 10:58 AM, "Tom Schouten" <tom at zwizwa.be> wrote:

>  Looks like this is the problem.
>
> > The usual reason for "out of memory" when running rsync is that you
> > are transferring a _very_ large number of files.  The size of the
> > files doesn't matter, only the total number of files.
> > http://www.infoscience.co.jp/technical/rsync/original/FAQ.html
>
> The problem only popped up after trying to back up my main PC.
> All the other backups are server VMs and a lot smaller in size.
>
> I ran into an additional problem: e2fsck uses a lot of memory on large
> file systems.
> It didn't work on the router, so I checked on a PC and the resident memory
> size for checking a 2G partition is 187m.
>
>
>
> On 07/29/2012 10:02 AM, Tom Schouten wrote:
>
> starting to run into trouble:
> Jul 28 09:33:56 zuk kernel: [315727.084000] rsync invoked oom-killer:
> gfp_mask=0x201da, order=0, oom_adj=0, oom_score_adj=0
> Jul 28 12:33:09 zuk kernel: [326479.124000] openvpn invoked oom-killer:
> gfp_mask=0x201da, order=0, oom_adj=0, oom_score_adj=0
>
>
>
> On 07/25/2012 01:41 PM, Bryan Laur wrote:
>
> I had thought you might be slightly overextending the capabilities of that
> device.
>
>  OpenWRT is optimized for the situation and as such, it's limitations are
> by design and aren't necessarily a flaw. (It's just a matter of using the
> right tool for the job.)
>
>  I'm glad you got it working though!
>
>
> On Mon, Jul 23, 2012 at 10:31 AM, Tom Schouten <tom at zwizwa.be> wrote:
>
>>  It works and I'm happy with the setup.
>>
>> The main plus point is that Debian's asterisk works without trouble after
>> some tuning.  I can now switch off the PC without worrying about the desk
>> phone.  Next to pbx and normal router functions it has a USB backup drive
>> attached to receive remote backups.
>>
>> It takes about 5W, so that goal is more than met.  Also it's cheap.  I
>> used this to purchase a 2nd one for experimentation. Total price was $20
>> for the router, $12 for the 16GB mini USB flash drive and about $100 for
>> the external USB backup disk.  Prices where amazon/newegg deals so might be
>> a bit higher now.
>>
>> Currently it starts standard OpenWRT config that serves as a backup
>> configuration.  From there it detects if the USB flash drive is present,
>> and will proceed booting into Debian, killing the OpenWRT deamons and start
>> the Debian ones.  I do keep the OpenWRT dropbear daemon running to be able
>> to log into the real root.  Debian ssh daemon logs into the Debian chroot.
>>
>> The downsides:
>>
>> - Needs A LOT of work to tune for memory use and make robust.  My
>> approach just starts a couple of daemons from the Debian chroot to keep the
>> memory usage low, so the rest of the Debian boot is done manually, i.e. I'm
>> not running the main Debian init script.
>>
>> - I'd advice to install a hardware serial console from the start.  The
>> board already has the 4-prong header soldered on it.  I broke it once after
>> I switched it to be my main router, cutting myself out due to some network
>> configuration error and a non-working (non-tested) failsafe.  Of course
>> this is just me not being careful.
>>
>> - Device is not supported in standard OpenWRT (yet).  I'm not sure if
>> this is just an organizational problem or if there are licencing issues.
>> Compiling it is a pita.
>>
>> - The main disappointment is that ssh/rsync is very slow.  I don't get
>> over 2MB/sec and the limit here seems to be CPU, but for my purpose this is
>> OK (receiving rate-limited incremental backups over the internet).
>>
>> - It seems to need swap to run some of the more resource-intensive Debian
>> apps.  Especially during "apt-get install" things can get out of hand.  I
>> have this swap on a USB flash drive which is not ideal.
>>
>> It was a nice learning experience, but I did not expect it to take so
>> long to get going.  In retrospect, what I have running as daemons can
>> probably be done in pure OpenWRT, but it sure is handy to have the
>> convenience of a Debian system even if somewhat slow and
>> memory-constrained.  OpenWRT is great for its intended purpose, but has its
>> limitations.
>>
>>
>>
>> On 07/05/2012 05:42 PM, Bryan Laur wrote:
>>
>> So, how is this working out?
>> Did this end up being a viable solution?
>>
>>
>> On Fri, Jun 22, 2012 at 1:57 PM, Tom Schouten <tom at zwizwa.be> wrote:
>>
>>> To run debian I had to recompile the image on this page
>>> http://manojpi.blogspot.com/2012/05/openwrt-on-belkin-share-max-n300.html
>>> and enable FPU emulation.  Compilation didn't go without problems so if
>>> anyone is interested in the .trx or the *.ipk, drop me an email (strip the
>>> [GLLUG] tag in the subject line).
>>>
>>>
>>>
>>> On 06/21/2012 07:02 PM, Tom Schouten wrote:
>>>
>>>> I bought the N300.  Let's see if I can scale down requirements a bit..
>>>>
>>>> Next is "debootstrap --foreign --arch mipsel squeeze squeeze" on a USB
>>>> 2.5"
>>>> Looking for more info I ran into this page:
>>>> http://wiki.debian.org/DebianWRT
>>>>
>>>> I used OpenWRT + chrooted Debian system a couple of years ago on an old
>>>> SimpleTech SimpleShare NAS.  Worked well only for very basic stuff since
>>>> the disk was very slow and the machine was a bit low on memory (32M).  The
>>>> Belkin has 64M so should be a little better, but still seems quite tight.
>>>>  I'm curious if it will run asterisk.
>>>>
>>>>
>>>> On 06/19/2012 12:38 AM, Charles Ulrich wrote:
>>>>
>>>>> Not a bad price for a hackable router, even if the stock firmware is a
>>>>> bit crap. I might grab one to be a wifi bridge.
>>>>>
>>>>> Also, what OpenWRT class? :)
>>>>>
>>>>> Charles
>>>>>
>>>>> On 06/18/2012 11:56 PM, Tom Schouten wrote:
>>>>>
>>>>>> Thanks a bunch for all the answers.
>>>>>>
>>>>>> In the OpenWRT class I ran into this one today, currently $19.97 on
>>>>>> amazon
>>>>>> Belkin Share Max N300
>>>>>> http://www.amazon.com/Belkin-Share-N300-Wireless-Router/dp/B004B1Z6EE
>>>>>> There are patches for OpenWRT
>>>>>>
>>>>>> http://manojpi.blogspot.com/2012/05/openwrt-on-belkin-share-max-n300.html
>>>>>>
>>>>>> Cheers
>>>>>> Tom
>>>>>>
>>>>>>
>>>>>>
>>>>>> On 06/18/2012 08:23 AM, Tom Schouten wrote:
>>>>>>
>>>>>>> Hi List,
>>>>>>>
>>>>>>> Recently I've been doing some math and found out that running a 100W
>>>>>>> machine 24/7 at my parent's back home cost me about 150 Euros/year
>>>>>>> (Belgian electricity is quite expensive, about 20 Eurocents/kWh more
>>>>>>> than double of what it is here). The 100W was measured with power
>>>>>>> meter over period of 24h so is probably quite accurate. Includes PC,
>>>>>>> GB ethernet switch + wireless router.
>>>>>>>
>>>>>>> Anyone have an idea of how to replace this with something more
>>>>>>> power-efficient?
>>>>>>> I recently ran into [1] which seems like a nice solution. Not sure
>>>>>>> about the power though.
>>>>>>> It probably can go lower still. This[2] might be nice too.
>>>>>>>
>>>>>>> The main purpose for the server is backup, VPN, asterisk, email with
>>>>>>> spamassassin+clamav, apache and to serve as print server and gateway
>>>>>>> for the home network, maybe also PLEX but that can also run on a
>>>>>>> "real" PC if necessary.
>>>>>>>
>>>>>>> [1]
>>>>>>>
>>>>>>> http://mocko.org.uk/b/2012/06/17/how-i-store-my-1s-and-0s-zfs-bargain-hp-microserver-joy/
>>>>>>>
>>>>>>> [2]
>>>>>>> http://www.androidauthority.com/via-android-pc-arm-49-dollars-88209/
>>>>>>>
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>>>>>>>
>>>>>>>
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>>
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