Jun 152014
 

This is a simple vertical groundplane antenna intended for mounting atop a 10m Squid Pole. These can be made to nearly any frequency you desire, and can be self-supporting if needed. The main limitation is the stiffness of the wire used.

The antenna gets its name as the original was one I quickly knocked up just prior to a horse endurence ride event that took place at Donnybrook in 2011. I was assisting Brisbane Area WICEN with the emergency communications at this event, and this antenna, worked very well. 10W was more than sufficient to get back to base on 2m FM.

The design is very simple. You’ll need some stiff copper wire, and a panel-mount BNC connector. I used some strands from a thick mains cable: this was being tossed out at a ham radio meeting some years back. The cable had a black plastic coating and inside were 7 strands of solid copper, each about 2mm thick. Perfect for small antennas.

Similar wire can be found in non-stranded house mains cable.

First step is to work out what length to cut the elements. They should all be roughly the same length. This can be calculated by the simple formula:

v=f\lambda

which if you take v as being the velocity of light in a vacuum (~3\times10^8 m/s; radio will travel a little slower through air, but who’s counting?) and f as being 147.050\times10^6 and solve for \lambda you get 2.04m as the wavelength.  We want ¼ of this, so I’ve aimed for 51cm long elements.

Don’t worry about them being perfectly straight when measuring, extra length is good at this point, you’ll want a good 2cm extra.  You can make a wire shorter, you can’t make it longer.

Measuring the elements

Measuring the elements

Measure and cut the 4 elements. 3 will become your groundplane, and the 4th the radiating element. Also cut off about 10cm or so, give or take, which will be the ground wire used to hook the groundplane elements to the BNC connector. Also add to your parts list, some small velcro strips: you’ll find these handy to strap the coax to the squid pole.

Procured parts

Procured parts

Start with the short piece of wire. You’ll want to bend it into a rough triangle shape, with loops of wire at the corners. The groundplane radials will loop through these holes. The excess wire should be coiled up to one side: this is the loop the squid pole will pass through. The BNC connector will be fitted in between the 3 small loops.

Ground wire

donnybrook-03-ground-wire Ground wire

Be sure you can still put the nut back on.

Take 3 of the four elements, and make a hook at one end. Pass this hook through each of the small loops in the triangle. Try to make them sit roughly straight out from the centre of the triangle, then solder each hook into the loop.

Hooking the radials

Soldering the radialsAttaching the radials

Having done this, put the BNC connector in and do the nut up tight. You can do away with the eyelet with the solder tag. To finish off, take your remaining element, make a hook just big enough to go around the centre pin of the BNC connector, then solder into place.

Preparing radiating element

Hooking radiating elementSoldering the radiating element Attaching the radiating element

To finish off, bend this until it is vertical. The antenna is now ready for tuning.

Completed untuned antenna

Completed untuned antenna

Double check the length is about right. It should be around the 51~52cm mark.

Checking length

Checking length (close) Checking length

To check the tuning, use a SWR meter or antenna analyser if you have one. Here, I used the built-in SWR meter on my Yaesu FT-857D. When using a SWR meter, ensure you’re running minimum power. The following are some results from my set.  It is at this point, you do any trimming of your antenna.  The following are without trimming the antenna, you’ll note that in most examples, the SWR is very low, just a point or so showing up on the left side of the screen.

On 2m:

donnybrook-13-test-144500 donnybrook-13-test-145500 donnybrook-13-test-146500 donnybrook-13-test-147500

On 70cm:

donnybrook-13-test-432100 donnybrook-13-test-433100 donnybrook-13-test-434100 donnybrook-13-test-438100 donnybrook-13-test-439100 donnybrook-13-test-440100

To mount the antenna on your squid pole, feed the tip of the squid pole through the remaining loop.  Bend the tip of the antenna around the tip of the squid pole.  Hook your coaxial cable to the BNC connector and use velcro straps at regular points to hold the coax to the side of the squid pole.

Mounted antenna

Mounted antenna

Recommended coax for this purpose is RG-195.  RG-58 will work, but is lossy, RG-213 and LMR400 are too heavy to use on a squid pole and will cause it to bend or collapse.

Update: This antenna performed quite well.  Saturday, we used it for 2m packet, providing a digipeater for the stations in our area in case they couldn’t reach the main node (at “the pineapple farm” just outside Imbil).  We had stable packet communications all day.  Since the stations around us found they could work the main node directly, we swapped antennas around and used it instead for a VHF/UHF cross-band voice repeater.  Signal reports were good through the Imbil state forest.

Jun 012014
 

Just a quick note. I’ve been getting a lot of spambots registering on this site of late. Probably at least 3 an hour.

Thus I have implemented a new policy. Inactive accounts older than a week 3 days old who have posted no comments will be deleted. I will quarantine the account, and can re-instate it should an account be mistakenly deleted.

The comment doesn’t have to be approved, it can be in moderation. If the comment is spam, the account and comment will be deleted upon discovery. So spambots, go ahead, it’ll let me hunt you sooner. Or don’t even bother creating the account, no one will see it so it’s a waste of time anyway.

May 282014
 

Entered into an eBay contact form.

Hi, Just a short note.

I am closing my account: the form that asks why didn’t really capture the true reason why I’m closing.

It’s not quite “identity theft”, but it is security-related.

I haven’t been using my eBay account, so I thought I’d set the password to something nice and *strong*. On the password change form, I noticed a 20-character maximum limit.

This was red flag no. 1.

Then I pasted a randomised password from a generator. The site complained I had forbidden characters.

This was red flag no. 2.

By placing limits on the size of password and its content, it is clear to me that eBay is *not* serious about making its systems truly secure, and that breaches like the one experienced recently will be a recurring event.

By hiding behind “proprietary encryption” it isn’t even serious about reassuring the public: good crypto doesn’t need secret algorithms to work well.

As there’s now very little I buy off eBay, I feel the time has come to say goodbye. If you ever do get your act together, I might consider returning, but until then, farewell.

Apr 142014
 

I just checked my email, and see this:

Return-Path: < …>
X-Original-To: …
Delivered-To: …
Received: by atomos.longlandclan.yi.org (Postfix, from userid 0)
	id 67204200E27C; Sun, 13 Apr 2014 23:05:55 +1000 (EST)
Subject: [Fail2Ban] SSH: banned 138.91.144.167 from atomos
Date: Sun, 13 Apr 2014 13:05:55 +0000
From: Fail2Ban < …>
To: …
Message-Id: <20140413130556.67204200E27C@atomos.longlandclan.yi.org>

Hi,

The IP 138.91.144.167 has just been banned by Fail2Ban after
5 attempts against SSH.


Here is more information about 138.91.144.167:


#
# ARIN WHOIS data and services are subject to the Terms of Use
# available at: https://www.arin.net/whois_tou.html
#


#
# The following results may also be obtained via:
# http://whois.arin.net/rest/nets;q=138.91.144.167?showDetails=true&showARIN=false&ext=netref2
#

NetRange:       138.91.0.0 - 138.91.255.255
CIDR:           138.91.0.0/16
OriginAS:       
NetName:        MICROSOFT
NetHandle:      NET-138-91-0-0-1
Parent:         NET-138-0-0-0-0
NetType:        Direct Assignment
RegDate:        2011-06-22
Updated:        2013-08-20
Ref:            http://whois.arin.net/rest/net/NET-138-91-0-0-1


OrgName:        Microsoft Corp
OrgId:          MSFT-Z
Address:        One Microsoft Way
City:           Redmond
StateProv:      WA
PostalCode:     98052
Country:        US
RegDate:        2011-06-22
Updated:        2013-10-03
Comment:        To report suspected security issues specific to 
Comment:        traffic emanating from Microsoft online services, 
Comment:        including the distribution of malicious content 
Comment:        or other illicit or illegal material through a 
Comment:        Microsoft online service, please submit reports 
Comment:        to:
Comment:        * https://cert.microsoft.com.  
Comment:        
Comment:        For SPAM and other abuse issues, such as Microsoft 
Comment:        Accounts, please contact:
Comment:        * abuse@microsoft.com.  
Comment:        
Comment:        To report security vulnerabilities in Microsoft 
Comment:        products and services, please contact:
Comment:        * secure@microsoft.com.  
Comment:        
Comment:        For legal and law enforcement-related requests, 
Comment:        please contact:
Comment:        * msndcc@microsoft.com
Comment:        
Comment:        For routing, peering or DNS issues, please 
Comment:        contact:
Comment:        * IOC@microsoft.com
Ref:            http://whois.arin.net/rest/org/MSFT-Z

OrgTechHandle: MRPD-ARIN
OrgTechName:   Microsoft Routing, Peering, and DNS
OrgTechPhone:  +1-425-882-8080 
OrgTechEmail:  IOC@microsoft.com
OrgTechRef:    http://whois.arin.net/rest/poc/MRPD-ARIN

OrgAbuseHandle: MAC74-ARIN
OrgAbuseName:   Microsoft Abuse Contact
OrgAbusePhone:  +1-425-882-8080 
OrgAbuseEmail:  abuse@microsoft.com
OrgAbuseRef:    http://whois.arin.net/rest/poc/MAC74-ARIN


#
# ARIN WHOIS data and services are subject to the Terms of Use
# available at: https://www.arin.net/whois_tou.html
#

Regards,

Fail2Ban
atomos ~ # grep 138.91.144.167 /var/log/auth.log ; zgrep 138.91.144.167 /var/log/auth.log-20140*.gz
Apr 13 23:05:40 atomos sshd[3143]: Did not receive identification string from 138.91.144.167
Apr 13 23:05:40 atomos sshd[3144]: SSH: Server;Ltype: Version;Remote: 138.91.144.167-1025;Protocol: 2.0;Client: JSCH-0.1.51
Apr 13 23:05:41 atomos sshd[3144]: SSH: Server;Ltype: Kex;Remote: 138.91.144.167-1025;Enc: aes128-ctr;MAC: hmac-md5;Comp: none [preauth]
Apr 13 23:05:41 atomos sshd[3144]: SSH: Server;Ltype: Authname;Remote: 138.91.144.167-1025;Name: support [preauth]
Apr 13 23:05:48 atomos sshd[3144]: Invalid user support from 138.91.144.167
Apr 13 23:05:48 atomos sshd[3144]: Postponed keyboard-interactive for invalid user support from 138.91.144.167 port 1025 ssh2 [preauth]
Apr 13 23:05:49 atomos sshd[3203]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=138.91.144.167 
Apr 13 23:05:51 atomos sshd[3144]: error: PAM: Authentication failure for illegal user support from 138.91.144.167
Apr 13 23:05:51 atomos sshd[3144]: Failed keyboard-interactive/pam for invalid user support from 138.91.144.16  port 1025 ssh2
Apr 13 23:05:51 atomos sshd[3144]: Postponed keyboard-interactive for invalid user support from 138.91.144.167 port 1025 ssh2 [preauth]
Apr 13 23:05:51 atomos sshd[3236]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=138.91.144.167 
Apr 13 23:05:54 atomos sshd[3144]: error: PAM: Authentication failure for illegal user support from 138.91.144.167
Apr 13 23:05:54 atomos sshd[3144]: Failed keyboard-interactive/pam for invalid user support from 138.91.144.16  port 1025 ssh2
Apr 13 23:05:54 atomos sshd[3144]: Received disconnect from 138.91.144.167: 3: com.jcraft.jsch.JSchException: Auth cancel [preauth]

Seriously, some dodgy ISP in Russia or Asia having a crack, I’ll ignore it. But a big company like you? I expect better behaviour.

Apr 122014
 

Well, it seems user interfaces are going around in circles again. Just recently, I’ve been meeting up with the Windows 8.1 style UI. One of my colleagues at work uses this as his main OS, we also have a VM image of Windows Server 2012 R2 (a 180-day evaluation).  One thing I will say, it’s a marginal improvement on Windows 8.  But is it all that new?

win2012r2

Now, the start screen is one of the most divisive aspects of the Windows 8 UI.  Some love it, some hate it.  Me?  Well the first incarnation of it was an utter pigsty, with no categorisation or organisation.  That has improved somewhat now that you can organise tiles into groups.

But hang on, where have I seen that before?

winnt31-1

That looks… familiar… Let me scroll over to the right a bit…

winnt31-2Ohh, how rude of me!  Allow me to introduce you to an old acquaintance…

winnt31-3This, is Windows NT 3.1.  What one might call the first real ancestor of Windows 8.1.  Everything that came before was built on DOS, Windows 8.1 basically calls itself Windows NT 6.3 beneath the UI.  This is the great-great-great-great-great-great-great-great-grandparent of today’s Windows desktop OS.  Yeah, it’s been that many releases: 8.0, 7, Vista, XP, 2000, NT 4, NT 3.51 and NT 3.5 all sit in between.

Now the question comes up, how is it different?  Sure there are similarities, and I will admit I exaggerated these to make a point.  The Program Manager normally looks more like this:

winnt31-4The first thing you’ll notice that the Program manager (the closest you’ll get to the “start screen”) doesn’t normally occupy the full screen, although you can if you ask it to.  In fact, it will share the screen with other things you might have open:

winnt31-5This is good for both novice and power user alike.  The power user is likely wanting to launch some other application and will be thinking about the job at hand.  The novice might have instructions open that they’re trying to follow.  In neither case, do you want to interrupt them with an in-your-face full screen launcher; a desktop computer is not a smartphone.

The shortcoming of the original Program Manager interface in terms of usability was that you were limited to two levels of hierarchy, with the top-level containing only program groups, and the lower level containing only program icons.  The other shortcoming was in switching applications, you either had to know the ALT+TAB shortcut or minimise/restore full-screen applications so you could see the other applications or their icons.  There was no status area either.

Windows 95 improved things in that regard, the start menu could show arbitrary levels and the taskbar provided both a status area and a screen region dedicated to window selection.  As the installer put it, changing applications was “as easy as changing channels on TV”.  (Or words to that effect.  I’ve ran the Windows 95 installer enough times to memorise two OEM keys off-by-heart but not well enough to remember every message word-for-word.)  Windows NT 4.0 inherited this same interface.

This remained largely unchanged until Windows XP, which did re-arrange some aspects of the Start menu.  Windows 2000/ME made some retrograde changes with respect to network browsing (that is, “My Network Places” vs “Network Neighborhood”[sic]) but the general desktop layout was the same.  Windows Vista was the last version to offer the old “classic” menu with it disappearing altogether in Windows 7.  The Vista/7 start menu, rather than opening out across the desktop as you navigated, confined itself to a small corner of the screen.  Windows 8 is the other extreme.

Windows 8, the start screen takes over.  There’s no restore button on this “window”, it’s all or nothing.  Now, before people point me out to be some kind of Microsoft-hater (okay, I do endulge in a bit of Microsoft-bashing, but they ask for it sometimes!) I’d like to point out there are some good points.

The Start screen isn’t a bad initial start point when you first log in, or if you’ve just closed the last application and wish to go someplace else.  It’s a good dashboard, with the ability to display status information.  It’s also good for touch use as the UI elements are well suited to manipulation by even the most chubbiest of digits.

What it is not, is a good launcher whilst you’re in the middle of things.  A more traditional Start menu with an item to open the Start Screen would be better here.  It also does a very poor job of organising applications: something Windows has never been good at.

So I guess you’ve all worked it out by now that I’m no fan of the Windows UIs in general, and this is especially true of Windows 8.1/2012 R2.  Not many UIs have a lower approval rating in my opinion.  The question now of course, is “how would I do things different”?  All very well to have an opinion about what I don’t like, and so far the IT industry has pushed back on Microsoft and said: “We don’t like this”.  The question is, how do they improve.

Contrary to what some might think, my answer is not to roll the UI back to what came in Windows 7.  The following are some mock-ups of some ideas I have decided to share.

Meet a desktop that for now we’ll call the “Skin The Cat” desktop.  The idea is a desktop that provides more than one way to perform typical actions to suit different usage scenarios.  A desktop that follows the mantra… “there’s more than one way to skin a cat”.  (And who hasn’t wanted to go skin one at some point!)  No code has been written, the screenshots here are entirely synthetic, using The Gimp to draw what doesn’t exist.

mockup-desktopSo here, we see the STC desktop, with two text editors going and a web browser (it’s a quiet day for me).  I’ve shown this on a 640×480 screen just for the sake of reducing the amount of pixel art, but this would represent a typical wide-screen form-factor display.

You’ll notice a few things:

  • Rather than having the “task bar” down the bottom, I’ve put it up the left side.
  • The launch bar (as I’ll call it) has two columns, one shows current applications, the other shows that application’s windows.
  • Over on the right, we have our status area, here depicting volume control, WiFi, battery and mail icons, and a clock down the bottom.
  • Bottom left is a virtual desktop pager.  (MacOS X users would call these spaces.)

Why would I break Microsoft tradition and use this sort of layout?  My usual preference is to have the launch bar up the top of the screen rather than down the side, as that’s where your application menus are.  However, monitors are, for better or worse, getting wider rather than taller.  So while there’s plenty of space width-wise, stacking bars horizontally leads to one being forced to peer at their work through the proverbial letter-box slot.  This leaves the full height for the application.

I group the windows by the application that created them.  All windows have a border and title bar, with buttons for maximizing, iconifying (minimising, for you Windows folk) and closing, as well as a window options menu button, which also displays the application’s icon.

So how does this fit the “skin the cat” mantra?  Well the proposal is to support multiple input methods, and to be able to switch between them on the fly.  Thus, icons should be big enough you can get your thumb onto them with reasonable accuracy, most common window operations should be accompanied by keyboard actions, and the controls for a window should be reasonably apparent without needing special guidance.  More importantly, the window management should stay out of the way until the user explicitly requests its attention by means of:

  • clicking on any title bar buttons or panel icons with the mouse
  • tapping on the title bar of a window or on panel icons with one’s finger
  • pressing an assigned key on the keyboard

Tapping on the title bar (which is big enough to get one’s finger on) would enable other gestures momentarily to allow easier manipulation with one’s fingers.  The title bar and borders would be enlarged, and the window manager would respond to flick (close), pinch (restore/iconify or maximise) and slide (move) gestures.

Tapping the assigned keyboard key or keystroke (probably the logo/”Windows”/command key, inference being you wish to do give the window manager a command) would bring up a pop-up menu with common window operations, as well as an option for the launch menu.

Now this is good and well, but how about the launcher?  That was one of my gripes with Windows for many years after all… Well let’s have a look at the launch menu.

mockup-launcherSo here we’ve got a user that uses a few applications a lot.  The launcher provides three views, and the icons are suggestive about what will happen.  What we see is the un-grouped view, which is analogous to the tiles in Windows 8, with the exception that these are just program launchers, no state is indicated here.

The other two views are the category view, and the full-screen view.  These are identical except that the latter occupies the full screen like the present start screen in Windows 8 does.  Optionally the category view (when not full screen) could grow horizontally as the tree is traversed.  Here, we see the full-screen version.  Over on the right is the same list of frequent applications shown earlier.  As you navigate, this would display the program items belonging to that category.

mockup-launcher-fullscrn

Here, we choose the Internet category.  There aren’t any program icons here, but the group does have a few sub-groups.  The “Internet” category name is displayed vertically to indicate where we are.mockup-launcher-fullscrn-inetLooking under Web Browsers, we see this group has no sub-groups, but it does have two program icons belonging to it.  The sub-group, “Web Browsers” is displayed vertically.  Tapping/clicking “Internet” would bring us back up to that level.mockup-launcher-fullscrn-inet-web

In doing this, we avoid a wall of icons, as is so common these days on Android and iOS.  The Back and Home links go up one level, and up to the top respectively.

The launcher would remember what state it was last in for next time you call it up.  So if you might organise specialised groups for given tasks, and have in them the applications you need for that task.  It’d remember you opening that group last time so you’d be able to recall applications as needed.

Window management is another key feature that needs to be addressed.  The traditional GUI desktop has been a cascading one, where dialogue boxes and windows are draw overlapping one another.  Windows 8 was a throw-back to Windows 2.1 in some ways in that the “Modern” (god I hate that name) interface is fundamentally a tiling one.

There are times when this mode of display is the most appropriate, and indeed, I use tiling a lot.  I did try Awesome, an automatic tiling window manager for a while, but found the forced style didn’t suit me.  A user should be able to define divisions on a given desktop and have windows tiled within them.  The model would be similar to how spreadsheet cells are resized and optionally merged.  A user might initiate tiled mode by defining the initial number of rows and columns (which can be added or subtracted from later).  They then can “snap” individual windows to groups of cells, resizing the divisions as required.  Resizing and moving a window would then move in units of one “cell”.

At the request of the user, individual windows can then be “floated” from the cellular layout allowing them to be cascaded.  Multiple windows may also occupy a cell group, with the title bar becoming “tabbed’ (much like in FluxBox) to allow selection of the windows within that cell group.

I haven’t got any code for the above, this is just some ideas I’ve been thinking about for a while, particularly this afternoon.  If I get motivated, we may see a “skin the cat desktop” project come into existence.  For now though, I’ll continue to do battle with what I use now.  If someone (commercial or open-source motivated) wants to try and tackle the above, you’re welcome to.  However, the fact the ideas are documented here means there is prior art (in fact, there is prior art in some of the above), and I’d appreciate a little attribution.

Apr 122014
 

Hi all,

Well, this week has given the security world quite a shake-up as a result of the OpenSSL Heartbleed bug.  I’ve got no reason to suspect my key has actually been compromised, but two things made me decide to revoke my old key and issue a new one:

  • It was quite old, dating from 2011.  I think I’ll be replacing them every 2~3 years from now on.  (new one after two years, old one revoked a year later)
  • I’ve got no way to really know if my system was penetrated or not, better to be safe than sorry.

The following is my new key (minus the UIDs, I don’t want to encourage the spam):

pub   4096R/10BDE3B7 2014-04-11 [expires: 2017-04-10]
Key fingerprint = 9804 EB67 F914 61DE 967D  A1B0 4DFA 1914 10BD E3B7

Right now I’m going through and changing some of my passwords, just to be on the safe side. Thankfully I use a few different passwords (I have “classes” of passwords which I use for different tasks) so those getting revealed is less of a problem than it may have been.

The other good news is that my SSH keys haven’t been compromised, I have been gradually replacing my old DSA one with new RSA ones, and hadn’t copied the private key to my server yet (although the public one was in authorized_keys).  That, and my CA key used for this site, was kept on another computer, so it should be okay.  I’ve generated new SSL keys just in case though.

The new GPG key is signed with my old one, you can trust that signature if you wish.  Don’t trust anything signed by it after this date however.

Now, to re-train my muscle memory with these new passwords.  (sigh)

Apr 032014
 

Well, lately I’ve been doing some development work with OpenNebula.

We’ve recently deployed a 3-node Ceph cluster which we intend to use as our back-end storage for numerous things: among them being VM storage.  Initially I thought the throughput would be “good enough”, 3 hosts each with gigabit links supplying VM hosts with gigabit backhaul links.

It’d be comparable to typical HDDs, or so I thought.  What I didn’t count on in particular was the random-read latency introduced by round-tripping over the network and overheads.  When I tried Ceph with just libvirt, things weren’t too bad, I was close to saturating my 1Gbps link.  Put two VMs on and again, things hummed along.  Not blistering fast mind you but reasonable.

I got OpenNebula talking to it easy enough.  We’re running the stable version: 4.4.  There are a few things I learned about the way OpenNebula uses Ceph:

  • OpenNebula uses v1-format RBDs (the Ceph default actually)
  • Since v1 RBDs don’t support COW clones, instance images are copied.
  • Copying a 160GB image in triplicate over gigabit Ethernet takes a while, and brought our little cluster to a crawl.

Naturally, we’re looking into beefing up the network links and CPUs on the storage nodes, but I’ve also been looking at ways to reduce the load on the back-end cluster.  One is through caching.  There are a couple of projects out there which allow you to combine two types of storage, using a smaller, faster block device to act as a cache for a larger, slower device.  Two which immediately come to mind: FlashCache and bcache.

bcache is on the TODO list, it has a few more knobs and dials to be able to play with, and shares a single cache device with multiple back-end devices, so might yet be worth investing time in.

Sébastian Han posted a guide on doing RBD caching using FlashCache, and so my work has largely been based on this initial work.  I’ve been hacking up a OpenNebula datastore management and transfer management driver which harnesses FlashCache and the newer v2 RBD format to produce a flexible storage subsystem for OpenNebula.

The basic concept is simple enough:

  • Logical Volume Manager, is used to allocate slices of a SSD to use as cache for back-end RBDs.
  • For non-persistent images, a new copy-on-write clone of the base image is created
  • A flashcache composite device is produced using the LVM volume as cache and the RBD as the backend
  • KVM/QEMU/Xen uses this composite device like a regular disk

The initial attempt worked well for Linux VMs, read performance initially would be between 20MB/sec and 120MB/sec depending on network/storage cluster load.  Subsequent reads would then exceed 240MB/sec.  Write performance was limited to what the cluster could do, unless you used writeback mode at which point speed picked up dramatically.

Windows proved to be a puzzle, it seems some Windows images have an odd way of accessing the disk, and this impacts performance badly.  In many cases, the images were of a sparse nature, with most of the content being in the first 8GB.  So I made sure to allocate 8GB chunks of my SSD, and performed what I call pre-caching: seeding the contents of the SSD with the initial 8GB (or however big the SSD partition is) of the image.

That picks up the initial boot performance by a big margin, at the cost of the image taking a little longer to deploy in the PROLOG stage.

For those who are interested, some early code is available via git.

bcache might be worth a look-in as it has read-ahead caching.  I haven’t done so yet.  I’d like to split the caching subsystem out and have cache drivers much like we have for datastore managers and transfer managers alike.  The same concept would work for iSCSI/CLVM storage or Gluster storage as it does for Ceph.

Mar 272014
 

Well, the search goes on. This saga started out initially as questions began about where MH370 had gone.

As if a large aircraft could just disappear into thin air.

There’s no question that the plane has crashed. Almost certainly it crashed out in the ocean, a particularly nasty stretch of ocean that’s home to some of the roughest seas.

Sure, they’ll have life rafts and other safety devices on board. Anyone caught out in the ocean for this long would be long dead by now. To the families of those on board, I do offer my condolences.

The question remains as to why this happened though. I was thinking about this, this morning. The plane was destined for Beijing. It is understood it crashed somewhere south-west of Perth.

Far be it from me to raise conspiracy theories, but it got me thinking: was someone on that plane trying to take an Al Queda-esque swipe at Perth?

Update: Discussing the thought here, we rather suspect the 2 hour long recording on the flight recorder will be largely silent. It’s too far west for Perth, although there might’ve been intentions to alter course later. Something caused the course for the autopilot to be set down south, and the plane flew more-or-less dead straight. There are questions being raised about one of the pilot’s marital situation, which might hint at a suicide attempt. I guess I’ll stop here, and let the authorities do their investigation.

Feb 252014
 

Hi all,

This is more a note to myself on how to configure stgt to talk to a Ceph rbd. Everyone seems to recommend patching tgt-admin: this is simply not necessary. The challenge is the lax way that tgt-admin parses the configuration file.

My scenario: VMWare ESXi virtual machine host, needing to use storage on Ceph.
I have 3 storage nodes running ceph-mon and ceph-osd daemons. They also have a version of tgtd that supports Ceph. (See the ceph-extras repository.)

The /etc/tgt/conf.d/${CLIENT}.conf configuration file. (I’m putting all the targets for ${CLIENT} here.)

# Target naming: iqn.yyyy-mm.backwards.domain.your:client.target
# where yyyy-mm: year and month of target creation
# backwards.domain.your: Your domain name; written backwards.
# client.target: A name for the target, since it's for one client here I name it
# as the client's host name then give the rest some descriptive title.
<target iqn.2014-02.domain.my:my-client.my-target-name>
    driver iscsi
    bs-type rbd
    backing-store pool-name/rbd-name
    initiator-address ip.of.my.client
</target>

For better or worse, I run the tgt daemon on the Ceph nodes themselves. Multipath I’m not sure about at this point, I’ve set up the targets on all of my Ceph nodes so I can connect to any, but I have not tested this yet.

To enable that target:

# tgt-admin -v -e

Then to verify:

# tgt-admin -s

You should see your LUNs listed.

Jan 112014
 

I noticed when I went looking for soundmodem that its homepage had disappeared off the face of the ‘net, and with it, its source code.

Thankfully, there were some traces of it still around. The Wayback Machine had all bar the source code, and Debian had the rest of what I was looking for.

So you can find a mirror of the old soundmodem site, along with the software at the following address.

http://soundmodem.vk4msl.yi.org/