device unbind

I don’t like writing about things I didn’t do. But in this case my colleagues at OLX are mentioning I shall document it, for others. We were in trouble with an EBS volume on AWS as we had 2 of them attached to a box, one supposedly released but not completely.

From AWS Web UI we saw that the device was released, but in the box we could still do the listing of the content of the mounted device. It was RO though… but still, unclean situation.

We first cleared the filesystem in memory cache, and at least that removed the data from within the filesystem tree structure… but we could still fdisk list the device… at this stage I went for the latest escalation solution in this domain… call Alessandro Rubini, co-author of Linux Device Drivers.

Solution suggested… go into /proc/sys device folder “xen”, then folder related to the device module “blkblock” or something similar… then in there, there were 2 symlinks, with the name/alias of the devices… this is basically the reference in memory of the mapping between the module and the device… it is kept in the MODULE_DEVICE_TABLE data structure. Echoing such string (unique to the device) into the “unbind” special file which is in the above followed folder, releases the datastructure and therefore the device without having to unload the module. There was another healthy device held by such module, therefore we couldn’t unload/load it to flush its state.

$ ls /sys/bus/xen/drivers/vbd/
bind module uevent unbind vbd-12345 vbd-98765
$ echo  vbd-98765 >/sys/bus/xen/drivers/vbd/unbind

Third Async Cats Meetup

incontro berlinese sulla gestione di team remoti

Async Cat Herding

Our third meetup will be slightly unusual in that instead of being a brief lunch session we’ll try and bring enough speakers together for an afternoon session. The idea was born at Europace: After our last meetup Stefan Rudnitzki approached me the idea of hosting a “complete afternoon meetup all around innovative management techniques over at Europace”. We quickly picked a date, reached out to interesting speakers and booked the meetup space.

Please make sure to register online.

As at least some talks will be German only, as such the announcement will be kept in German below.

Innovative team management techniques Meetup @ Europace

Hallo zusammen,

die Europace AG plant gemeinsam mit Async Cat Herding am 28. Februar 2017 einen Nachmittag rund um das Thema innovativer Team Management Methoden. Das Ganze findet bei der Europace AG (eine Tochter der Hypoport AG) in der Klosterstraße 71 in Mitte statt. Euch…

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i2c_hid & cryptdevice

you’ll find lots of people complaining about luks, cryptdevice, grub and a damn usb keyboard… now, the fun comes with new laptops like the one i’m playing with

first of all it has on board a cursed SoC called baytrail (renamed bayFAIL by most of the people on the internet) …. second, well…. whatever… you are on your own … as me, as always

the laptop is a Lenovo 100S, it comes for 199EUR off the shelf in any electronics store in Germany… and to install, go straight to a Debian Testing amd64+i386 DVD iso… to be dd-ed onto a usb stick. Don’t use a non-multiarch installer, the EFI will be ur enemy. It won’t boot 😉

so…. the solution for the damn keyboard… once installed… and once you logged in with an external usb keyboard is to modify the /etc/initramfs-tools/modules and add the following:

i2c_designware_platform
i2c_designware_core
i2c_algo_bit
i2c_hid

then just type:

update-initramfs -u

and reboot

…yes, you are welcome

is the Galaxy S6 Edge the only LTE phone for US/EU travellers?

I mean, I live in Germany, but I work for an american company based in Orange County (Southern California, USA) and Verizon seems to be the king over there as the CDMA technology allows them to cover 10 times the range of what a GSM tower can cover. Verizon is NO option for a european like me as to have their simcard you need to have a phone that they purchased in batches and registered in their infrastructure. You cannot bring in your own phone, even if the tech specs of the phone are fine. You simply can’t. Well, they won’t you let BYOD (bring your own device). Unless it is an iPhone 6s [probably Apple forced them to preemptively register all their IMEIs in the network]

Anyhow…

If you are living in Germany, you do need a phone that has the LTE FDD frequencies 3,7 and 20 (in MHz 1800, 2600 and 800) according to https://en.wikipedia.org/wiki/List_of_LTE_networks_in_Europe

If you live in Italy, same set of frequencies.

If you wanna travel to US, and don’t wanna have to purchase a phone from Verizon (it will take you at least 6 months of contract with them to get it unlocked… so, until you can put in your italian/german simcard) you have to go for T-Mobile. Therefore… frequencies LTE FDD 2,4 and 12 (again in MHz 1900, 1700 and 700a -> no clue what’s the “a” stands for) Check https://en.wikipedia.org/wiki/List_of_LTE_networks#Americas for further details.

Well… the only phone that has LTE FDD frequencies 2,3,4,7,12,20 all in one, is the Samsung S6 EDGE -> http://www.samsung.com/us/explore/galaxy-s-6-features-and-specs/

It also has at least one match for Docomo (Japanese carriere) required frequencies: LTE FDD 1 (2100 MHz) … forget about the others: 9(3), 19(5,26) and 28. It was already a miracle for me to put my hands on a prepaid “data only” simcard while in Tokyo on spring last year. Apparently you cannot have a “voice” simcard unless you are a resident…

Has anybody else found another phone suitable for a “global traveller”? Possibly cheaper than the S6 😉 …and maybe dual-sim too… k, now I’m asking too much I guess. 😀

UPDATE: [strike out 1] The Nexus 5X as it has all the frequencies I need plus it is a an LTE Cat 6 phone [strike out 2] The Sony Xperia Z5 (it has also an internal microSD slot) The Motorola Moto X Style (more cost effective, and has up to 128Gb microSSD card slot) is most likely to be my next phone. Thanks to Fra Costa for introducing me to Project Fi (very cool indeed, but I’m not US based). Here is a list of all the other LTE Cat 6 devices…  (not only Cat6)

 

 

cervelli in fuga

(Copio e incollo dal post su facebook. Sono felice di aver fatto parte del progetto)
Aladino A. Amantini: Sono molto fiero di questo video. Quasi quanto lo sono dei miei amici

Con la partecipazione di (tra gli altri):

Se siete interessati a Sailing Film, il progetto di Jacopo: http://www.sailingfilm.com
Se siete interessati ai progetti tecnici di Renato: https://www.facebook.com/xevilstar
Se siete interessati a Gaia Italia, il progeto di Giacomo: http://www.acquarishop.it
Se siete interessati ad andare a lavorare in Olanda con Fernando e Andrea sentite me (da oggi cacciatore di teste)
Music Title: brain Author Frankie C
Licence: Creatice Commons 3.0 (Attribution – No Derivative Works)

partially qualified domain names, OS X Yosemite v10.10.1

Apple broke DNS compatibility towards partially qualified domain names with the latest OS X release. On Nov. 18th they released an update with a patch to this issue (since I spent the time to escalate it). From http://support.apple.com/en-us/HT204017 release notes I quote:

Allows you to append search domains for partially qualified domain names when performing DNS lookups (consult the discoveryd man page for more information)

How was it supposed to work? And how can we activate it?

If you are a big corporation you are going to have a very complicate and hierarchically designed DNS system. Sometimes you just want to shorten the amount of data you type in to jump from one box to another, so… taking as a sample the Akamai mirror of apple.com you’ll see that will CNAME to e3191.dscc.akamaiedge.net. Imagine you are working for Akamai, and you need to ssh into e3191.dscc , without the partially qualified domain name feature you’ll have to type in the full fqdn. Instead, if you have akamaiedge.net in your domain search field, you don’t have to, your resolver will do it for you.

So, on OS X… I quote from my Apple Support guy’s email:

You can edit /System/Library/LaunchDaemons/com.apple.discoveryd.plist and add ‘–AlwaysAppendSearchDomains’ as a string to the ‘ProgramArguments’ array. That should re-enable search domains for PQDNs once you reboot after saving.

I add… you can simply “sudo launchctl unload /System/Library/LaunchDaemons/com.apple.discoveryd.plist” and “load” to refresh the daemon after having edited the file, without rebooting your laptop/workstation…

enjoy 😉

offro lavoro

abbiamo budget per l’assunzione di 3 persone in Sony Playstation
datacenter engineer https://www.linkedin.com/jobs2/cap/view/13220463
(
sospesa sino ad agosto… per il momento non stiamo conducendo colloqui)
– network engineer https://www.linkedin.com/jobs2/view/13274419
– security engineer* https://www.linkedin.com/jobs2/view/10603940
* si, lo so che il job posting e’ per gli states, ma c’e’ la posizione gemella a Berlino

vi faccio io un prescreening in inglese via skype (il mio ID e’ zeph1ro, aggiungetemi),
non mandatemi curriculum in italiano perche’ finiranno direttamente nel cestino 😉
(si, ho scritto questo post in italiano per intercettare le vs ricerche su google)

p.s. lo aggiungo (non si sa mai), https://www.linkedin.com/jobs2/cap/view/12896708
posizione della madonna come *SENIOR* C++ developer, ma dovete avere il visto USA