drobo mini performance issue

I had looking for a portable high capacity storage system for a while and turns out there are two popular in the market. Drobo Mini, and the Pegasus J4 from Promise. I finally grab this drobo mini because of the recent price drop from 660US to 320US… very attractive price!

Very Slow Overall!

At the first time, I reuse my existing 2 x 5400rpm Toshiba 1TB harddisk and 2 x WD 5400rpm 500GB harddisk, I inserted them and format it as 8TB target size. Open the blackmagicdesign disk testing tool, the result is ~120MB write / ~60MB read? that is very slow! Then I read the recommendation from drobo website to add a msata SSD for acceleration, so I added a 128GB crucial m4 SSD. Re-run the test without any improvement.

Getting better in write performance

Later, I bought two latest Hitachi 7200RPM 1TB harddisk to replace the 500GB WD harddisk, by swapping the disk one by one and wait the rebuild complete, I rerun the test, the result shown ~160MB write / ~75MB read. It still darn slow! why?

Trying to figure out the root cause

I’d decide to give it a last try to replace the left by 5400rpm harddisk to the same Hitachi 7200rpm 1TB harddisk, same by swapping one by one and let it rebuild. rerun the test, the result shown ~220MB write / ~90MB read. Still very very slow, even slower the single drive.

Reset works!!

When i was really disappointed with no cure to manage it,  I press the reset button in the drobo dashboard, reformating it and rerun the test. Oops!? the result pop up ~210MB write/~260MB read! that is what I’m expecting.

Slow performance come back

When i was so exciting and transferred all file (~1TB)  back to the drobo, I rerun the disk test to ensure the drobo is in good shape, however the turn me down again. The read performance drop dramatically again, but not worst as ~90MB read, it still had ~160MB to ~200MB read inconsistently. So I’m going to find out why again. That is troublesome, and no answer in google.

Format SIZE is somehow do the trick!

I start to drill into the disk size may affect the performance, I format the drobo as 4 TB , 8TB and 16TB for testing, each time I record the performance after a fresh format and after copy those 1TB data (~200k files). The result as below

Fresh formatted  (4 x 1TB RAW)

Formatted Size Write (MB/s) Read (MB/s)
4TB 231 302
8TB 213 265
16TB 209 221

After 1TB data (~200k files)

Formatted Size Write (MB/s) Read (MB/s)
4TB 192 251
8TB 170 208
16TB 143 197

As the above result, you see the more close to raw size the more speed.


SSD accelerator size in comparison

Many people asking how the accelerator bay SSD size affects the drobo performance, I’d borrowed another 64GB and 256GB Plextor M5 SSD for the comparison, and I’m telling you solidly, there are NO different I can tell in backmagic disk test tool, AJA nor Xbench, don’t spent too much money on this SSD, just 64GB will be fine.



DIY Fujifilm X-M1 wireless shutter release control

Wireless shutter release for X-M1

Fujifilm X-M1 out of box do not equip a remote shutter remote or capability for third parties. You have only one choice  (RR-90) USB wired remote. As I owned X-E1 in few months ago, X-E1 works with Canon E3 compatible remote shutter release and I found that RR-80 USB (for X-E1) wired remote is a analog signal control (see http://www.trafficshaper.com/RR-80/RR-80.html). Therefore guessing X-M1 will reuse the same mechanism as X-E1, so I tried to figure out the PIN combination to simulate RR-90 and then try to integrate it with a Canon E3 compatible remote shutter release.

What you need

1. 2.5mm Jack cable 2. Micro USB Male Plug
3. Canon E3 CompatibleShutter Release (Wireless/Wired) 4. Soldering tools


2.5 Jack PIN Micro USB PIN
Tip(Red) 5
Ring(White) 4
Ground(Black or sheild) 1

Pin explanation

Operation Combaination
AF (Haft-Press) Pin1 + Pin 4
Shutter Release (Full-Press ) Pin5 + Pin 4


Reborn your Roland CY-8 Cymbals

Playing your Roland CY-8 Cymbal time by time, it will becoming lack of sensitivity, you have to hit it very hard to trigger the sound. It is because oxidation is happening on the sensor inside the cymbal pad.

To fix it in very low cost without replacing a brand new pad, you may just buy a 27mm Piezo Elements Sensor from ebay, and then just replace the sensor disc inside the pad. Using a solder gun, detach the old disc and replace a new one. That’s it. The new disc will work like a charm.

For the soldering tools, I suggest you to use a ~45W solder gun, beware overheating will damage the disc. Never hold the heat on the disc longer than 5sec.

TCP High Performance Networking Options

High Performance Networking Options

The options below are presented in the order that they should be checked and adjusted.



Maximum TCP Buffer (Memory) space: All operating systems have some global mechanism to limit the amount of system memory that can be used by any one TCP connection. [more][less]

Socket Buffer Sizes: Most operating systems also support separate per connection send and receive buffer limits that can be adjusted by the user, application or other mechanism as long as they stay within the maximum memory limits above. These buffer sizes correspond to the SO_SNDBUF and SO_RCVBUF options of the BSD setsockopt() call. [more][less]

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XML errors when document contain UTF control character HEX 0x??

When you getting errors NSXMLParserErrorDomain kind of errors in iphone and tired to resolve the problem with your wordpress site, that error usually caused by invalid UTF character in your post.

The easiest way prove that, you can publish few blog post with blank content, and then re-save your iphone blog setting following your each blank post. Once get it pass the saving progress in iphone you should know which blog post including invaild character.



what is vglock?

A vg used as cluster lock is generally called vglock. cluster lock refer to a tie breaker short of thing which is generally used in a two node service guard cluster. In the event of failure of communication between two nodes whoever takes control of lock first will continue to run cluster and other node will be halted.

Hence the purpose of this is to ensure both nodes independently form two seperate clusters in the even of failure of communication among them.

How to measure network transmit speed?

FTP speed restricted by its limitation. You cannot rely on the result made by FTP, especially when you transmit data with using high speed network.
Secondly, to avoid disk I/O bottlenet when performing network speed measurement, you should use dd from /dev/zero to /dev/null
In this case, I use a pipe file as source data and used ssh to read the file. The result likely consistent.

Data size 1024 MB

Case A 100/NIC to 100/NIC  = 94 sec
Case B 1000/NIC to 1000/NIC = 27 sec
Source Machine – machine1 (data)

1. Make a pipe file in /tmp
mknod /tmp/applepipe p

2. dd 1GB data into the pipe file
dd if=/dev/zero bs=8k count=128000 of=/tmp/applepipe

Client Machine ( Read )
timex ssh machine1 “dd if=/tmp/applepipe bs=8k”|dd of=/dev/null bs=8k

vi quick sheet

learn vi…… you’ve to remember many command and key……

Starting and Ending VI

Starting VI
vi filename Edits filename
vi -r filename Edits last save version of filename after a crash
vi + n filename Edits filename and places curser at line n
vi + filename Edits filename and places curser on last line
vi +/string filename Edits filename and places curser on first occurance of string  
vi filename file2 Edits filename, then edits file2 … After the save, use :n
Ending VI
ZZ or :wq or :x Saves and exits VI
:w Saves current file but doesn’t exit
:w! Saves current file overriding normal checks but doesn’t exit
:w file Saves current as file but doesn’t exit
:w! file Saves to file overriding normal checks but doesn’t exit
:n,mw file Saves lines n through m to file
:n,mw >>file Saves lines n through m to the end of file
:q Quits VI and may prompt if you need to save
:q! Quits VI and without saving
:e! Edits file discarding any unsaved changes (starts over)
:we! Saves and continues to edit current file

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