[GLLUG] Low-power Home Server
Tom Schouten
tom at zwizwa.be
Sun Jul 29 10:58:59 EDT 2012
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
>> <mailto: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
>>> <mailto: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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