Tranquil PC's Weblog

 

The Safe Server Module

Imaging, backups, Add Ins, remote files ….. What is the simplest, lowest cost, real time solution to the Safe Server requirement ?

After much searching, testing, brain storming – the answer was right in front of us. 

Back in the Summer of 2009, Tranquil designed an ultra reliable system for a large (global) company.  The systems had to be reliable – each one controlled a robotic system making a very expensive product – and there were 100’s of machines to be deployed.  If a robotic system went down, the line down time was extremely expensive (talking here of 5 or 6 digits of Euro’s per hour) !

The system had numerous components selected to enhance reliability, but the HDD redundancy was taken care of by a custom simple hardware RAID 1 controlled device, it provided hardware mirroring of the 2x 2.5” HDDs in real time.  Better still there was no user intervention (GUI) required – if a HDD failed, just pop in a new one for continuous operation, the 2nd HDD just re-built itself.

 

Now could this device, protect a Home Servers Primary HDD ?

For the last 6 months Tranquil have a number SQA-5H Home Servers fitted with the SSM on load / cycle test to prove it ‘just works’.  All results are very encouraging (zero faults)

As the unique device can be plugged into a SQA-5H Home Servers HDD1 bay, it seems the solution ticks all the right boxes.

• Simple – it just replaces a SQA-5H HDD module
• Low cost – it does have a cost overhead, but it’s far cheaper than the alternatives
• Real Time – it’s a real time hardware based RAID1 mirror device (no issues with WHS DE)

There are some limitations to be aware of :

• The maximum capacity of the Safe Server Module is 500GB
• The HDD LED activity above the bay is replaced by HDD activity indicators on the module (visible behind the grill of the HDD front)

 

Rebuild process / times

In the event that a HDD in the Safe Server Module fails, or you want to carry out a scheduled exchange, the process is simple.

• Identify the HDD you want to exchange (HDD0 or HDD1)
• Depower the Server
• Remove the Safe Server Module from the SQA-5H (just like removing a regular 3.5” HDD)
• Snap out the HDD module
• Eject / replace the old HDD
• Replace the unit into the SQA-5H server
• Power on

The Safe Server Module immediately starts to rebuild, whilst the SQA-5H re-boots in the normal fashion.  If you look carefully at the Safe Server Module (behind the grill), you will see a blinking green/red LED – this is the rebuild / verification process.  Once the LEDs all go green, the process is complete.

Times vary, but a 500GB HDD Module will take between 4.5 and 5.0 hours for a complete rebuild / verification.  The SQA-5H is fully operational during the re-build / verification process.

 

Disk Performance

Does the Safe Server Module design hinder performance ?  We have tested a standard T7-WHS-D Home Server unit (Samsung 2.5” HDDs) against the SQA-5H fitted with the Safe Server Module – see the results below :

HDD benchmark (2.5” Samsung HDD in Standard Home Server setup) – below :

 

HDD benchmark (2.5” Samsung HDD in SQA-5H Safe Server Module setup) – below :

 

The results indicate overall similar performance (except for buffered read, where the Safe Server Module was slower)

 

 

Next – how to monitor the Safe Server Module, and how it keeps in touch with you