Forced choice (VirtualBox, or Docker)

In order to run Docker, it seems I must discontinue my use of VirtualBox. Great (not great); e.g.,


CentOS: Forced shutdown

Yesterday, we encountered a disk issue on one of our CentOS servers. Some of the disks had either failed, or were predicting failure, so our vendor swooped in, changed some of the disks, as well as the RAID controller. Unfortunately, this worked for only a short time, before we started seeing “input/output error” verbiage in the console. The concern was data loss, so we tried to shutdown, reboot: same “input/output error”.

And then I learnt that it’s possible to force a shutdown via the Magic SysRq key. I mean, magic!!

echo 1 > /proc/sys/kernel/sysrq
echo o > /proc/sysrq-trigger

New disks are incoming as I type this, we’ll have to keep a close look on this developing situation.


Oracle: Cleaning up SYS_EXPORT_SCHEMA_xx jobs

Sometimes expdp jobs fail for any number of reasons. Re-running expdp, I noticed that the number had increased since the prior run; e.g., SYS_EXPORT_SCHEMA_02 instead of SYS_EXPORT_SCHEMA_01. As it turns out, these are potentially orphaned jobs, so clean ’em up!

Generally, copied from Anar Godjaev’s excellent blog post:

SQL> select owner_name, job_name, operation, job_mode, state, attached_sessions from dba_datapump_jobs;

SQL> drop table {owner_name}.SYS_EXPORT_SCHEMA_01;
SQL> purge table {owner_name}.SYS_EXPORT_SCHEMA_01;


Oracle: ORA-00257 archiver error. Connect internal only, until freed

Work around for this issue is to increase the amount of space allocated to db_recovery_file_dest; e.g.,

$ sqlplus sys as sysdba
SQL> show parameter db_recovery_file;
db_recovery_file_dest string /opt/oracle/flash_recovery_area
db_recovery_file_dest_size big integer 20G

Compare this with the output of ‘du -sh’; e.g.,

$ du -sh /opt/oracle/flash_recovery_area
21G /opt/oracle/flash_recovery_area

21 vs 20, so set it to something a bit bigger; e.g.,

SQL> alter system set db_recovery_file_dest_size = 30G;

Extracted from this link on

#linux, #oracle

Apple Special Event

Apple Park, it starts with the first event held today at the Steve Jobs Theatre.

Today at Apple, it seems to be huge. I can’t attest to this though, haven’t been at the Orchard Road one.

Apple Watch
No. 1 apparently, leapfrogging Rolex. New heart rate metrics (e.g., resting heart rate, recovery rate) in watchOS 4.

Next generation Watch, series 3. Built-in cellular connectivity (eSIM), so you can remain connected whilst away from the phone.

New dual-core processor, additional W2 chip. Same height/width, but slightly thicker in order for battery life to remain consistent.

Live FaceTime call seems pretty good in spite of tenuous source condition. $329/399 without/with cellular. Launches without carrier support in Singapore, though.

Apple TV
Next generation Apple TV ($179), support for 4K content. High Dynamic Range (HDR), for vivid colors. Same A10X SoC used in iPad Pro.

Live sports content, wow!

Access HomeKit devices, it’s always at home anyway.

Game demo seems pretty cool, works well with the touch remote.

iPhone 8, & iPhone 8 Plus
Glass front and back, plus aluminum. Comes in silver, space grey, and gold.

True Tone, like for iPad Pro.

New SoC, they call it A11 Bionic (read: faster).

8 Plus portrait lighting mode seems awesome.

ARKit, coming in useful for gaming!

Leverages the existing Qi wireless charging. -death keel for competing standards-

iPhone 10
Edge to edge Super Retina display. 5.8″, 458 pixels per inch, OLED.

No more Home button, so swipe up from the bottom. Swipe down from the top to access Control Centre.

To unlock your phone, just look at it (Face ID). A whole bunch of sensors at the top, some of it in support of Face ID. Probably won’t work with 😎, though.

Neural engine, additional to A11 Bionic. Won’t be faked out by photographs or masks. Sorry, Arya of House Stark.

Animoji on iMessage, pretty cool. I call dibs on the 💩 Animoji.

Camera tech. is even more advanced than 8 Plus.

2 hours more of battery life, great!

3 devices charging at the same time: iPhone, AirPods, and Apple Watch; i.e., AirPower. And I thought it meant superior fighter jets and helicopters.


Linux: Ifconfig and its replacement

Recently I installed CentOS 7 Minimal, and lo and behold, command not found. As it turns out, ifconfig while you can still get via ‘yum install net-tools‘, we should be a bit more forward looking, and use it’s designated replacement.

To quote Doug Vitale’s excellent article:

some Linux tools that, while still included and functional in many Linux distributions, are actually considered deprecated and therefore should be phased out in favor of more modern replacements.

Specifically, the deprecated Linux networking commands in question are: arp, ifconfigiptunnel, iwconfig, nameif, netstat, and route. These programs (except iwconfig) are included in the net-tools package that has been unmaintained for years.

Now, his article was written in 2011, so this probably means a decade or so after the software was essentially abandoned, there are still unknowing users like me who had no idea, happily using it for whatever we use it for.

So software and blog posts, the gift that keeps on giving then!


Hiding page breaks in Excel

I’d successfully hidden ’em distracting grid lines in Excel via (Ribbon) > View > Gridlines, but then I wanted to hide (similarly distracting) page breaks. As it turns out, this option is pretty well hidden:

File > Options > Advanced > Display options for this worksheet > Show page breaks

Also note that this option is set on a per-worksheet basis, so you’ll have to uncheck once for every worksheet you may have. Thankfully, there is a drop list 3 check boxes above, so just rinse and repeat.

Kudos to the ExtendOffice blog post for this enlightenment: