The WOW Factor

I remember the first editions of VMworld: technologies like vmotion and FT made you just standing still thinking "WOW!".
That "WOW factor" had faded away in later editions: virtualization technology is now a consolidated thing and I've not seen anything really breathtaking.
The last two editions were really all about the cloud (yawn!) and just some other little incremental improvements.
Finally, I saw something that could bring a revolution in the way virtualization clusters are built:
SimpliVity Omnicube and Nutanix Complete Cluster.
It's WOW time again...

How to check if a variable contains a string

string="this string contains a test substring"

if [[ "$string" == *test* ]]
then
        print "substring found"
fi 

Bye bye Internet Explorer, Chrome on the rise.

It's been an year since this blog was up and running.
Time to take a look at the stats:

Firefox (39%)
Chrome (30%)
Internet Explorer (17%)
Safari (5%)
Others (9%)

Desktop (91%)
Mobile (9%)

Despite all the claims, mobile browsing is still lagging behind desktop.

RAID 5 write performance

Everybody knows that RAID 5 has poor write performance, but how much?
With some spare parts at my disposal, I've done some testing:
Here is a RAID 5 volume, built with 7 SAS drives, each one is 146GB @ 10K rpm.
The controller is an HP Smart Array P400


[root@test /]# dd if=/dev/vg_99/lv_share of=/dev/null bs=1024 count=10240000
10240000+0 records in
10240000+0 records out
10485760000 bytes (10 GB) copied, 40.097 s, 262 MB/s
[root@test /]# dd of=/dev/vg_99/lv_share if=/dev/zero bs=1024 count=10240000
10240000+0 records in
10240000+0 records out
10485760000 bytes (10 GB) copied, 500.826 s, 20.9 MB/s

So, 262 MB/s reading vs 20.9 MB/s writing.