| Andrew Cooke | Contents | Latest | RSS | Twitter | Previous | Next


Welcome to my blog, which was once a mailing list of the same name and is still generated by mail. Please reply via the "comment" links.

Always interested in offers/projects/new ideas. Eclectic experience in fields like: numerical computing; Python web; Java enterprise; functional languages; GPGPU; SQL databases; etc. Based in Santiago, Chile; telecommute worldwide. CV; email.

Personal Projects

Lepl parser for Python.

Colorless Green.

Photography around Santiago.

SVG experiment.

Professional Portfolio

Calibration of seismometers.

Data access via web services.

Cache rewrite.

Extending OpenSSH.

C-ORM: docs, API.

Last 100 entries

Small Success With Go!; Re: Quick message - This link is broken; Adding Reverb To The Echo Chamber; Sox Audio Tools; Would This Have Been OK?; Honesty only important economically before institutions develop; Stegangraphy via PS4; OpenCL Mess; More Book Recommendations; Good Explanation of Difference Between Majority + Minority; Musical Chairs - Who's The Privileged White Guy; I can see straight men watching this conversation and laffing; When it's Actually a Source of Indignation and Disgust; Meta Thread Defending POC Causes POC To Close Account; Indigenous People Of Chile; Curry Recipe; Interesting Link On Marginality; A Nuclear Launch Ordered, 1962; More Book Recs (Better Person); It's Nuanced, And I Tried, So Back Off; Marx; The Negative Of Positive; Jenny Holzer Rocks; Huge Article on Cultural Evolution and More; "Ignoring language theory"; Negative Finger Counting; Week 12; Communication Via Telecomm Bids; Finding Suspects Via Relatives' DNA From Non-Crime Databases; Statistics and Information Theory; Ice OK in USA; On The Other Hand; (Current Understanding Of) Chilean Taxes / Contributions; M John Harrison; Playing Games on a Cloud GPU; China Gamifies Real Life; Can't Help Thinking It's Thoughtcrime; Mefi Quotes; Spray Painting Bike Frame; Weeks 10 + 11; Change: No Longer Possible To Merge Metadata; Books on Old Age; Health Tree Maps; MRA - Men's Rights Activists; Writing Good C++14; Risk Assessment - Fukushima; The Future of Advertising and Surveillance; Travelling With Betaferon; I think I know what I dislike so much about Metafilter; Weeks 8 + 9; More; Pastamore - Bad Italian in Vitacura; History Books; Iraq + The (UK) Governing Elite; Answering Some Hard Questions; Pinochet: The Dictator's Shadow; An Outsider's Guide To Julia Packages; Nobody gives a shit; Lepton Decay Irregularity; An Easier Way; Julia's BinDeps (aka How To Install Cairo); Good Example Of Good Police Work (And Anonymity Being Hard); Best Santiago Burgers; Also; Michael Emmerich (Vibrator Translator) Interview (Japanese Books); Clarice Lispector (Brazillian Writer); Books On Evolution; Looks like Ara (Modular Phone) is dead; Index - Translations From Chile; More Emotion in Chilean Wines; Week 7; Aeon Magazine (Science-ish); QM, Deutsch, Constructor Theory; Interesting Talk Transcripts; Interesting Suggestion Of Election Fraud; "Hard" Books; Articles or Papers on depolarizing the US; Textbook for "QM as complex probabilities"; SFO Get Libor Trader (14 years); Why Are There Still So Many Jobs?; Navier Stokes Incomplete; More on Benford; FBI Claimed Vandalism; Architectural Tessellation; Also: Go, Blake's 7; Delusions of Gender (book); Crypto AG DID work with NSA / GCHQ; UNUMS (Universal Number Format); MOOCs (Massive Open Online Courses); Interesting Looking Game; Euler's Theorem for Polynomials; Weeks 3-6; Reddit Comment; Differential Cryptanalysis For Dummies; Japanese Graphic Design; Books To Be Re-Read; And Today I Learned Bugs Need Clear Examples; Factoring a 67 bit prime in your head; Islamic Geometric Art; Useful Julia Backtraces from Tasks; Nothing, however, is lost with less discomfort than that which, when lost, cannot be missed

© 2006-2015 Andrew Cooke (site) / post authors (content).

RAID on SuSE Linux 10.2

From: "andrew cooke" <andrew@...>

Date: Sun, 4 Mar 2007 21:12:44 -0300 (CLST)

In retrospect, software RAID in Linux is easy.  If you're doing a clean
install there's nothing to it.  However, I couldn't (for a long time) find
anything that said this.  So I read explanations about RAID technology and
wondered how on earth I could boot from a software RAID - it seemed like a
chicken and egg situation unless you went with simple mirroring, which was

So I started by trying to install the OS on a separate PATA disk (the
P5LD2 has a single parallel IDE controller that is intended for CD/DVD). 
Luckily this failed (Grub crashed) and when I went to the SuSE IRC channel
some jerk knew enough to imply I was an idiot, but not enough to answer
any questions.

Still, it was useful to know I was wrong.  Searching some more I found
this page -
http://en.opensuse.org/How_to_install_SUSE_Linux_on_software_RAID -
(obvious in retrospect, but I turned it up only when I switched googling
from "suse" to "opensuse").  That was enough to make me realise I had
missed a "RAID button" on the installer interface.

In fact, I hadn't missed it - I just didn't realise how powerful it was.

So here's what I did - it uses just the 4 identical SATA disks I bought
and it gives you a system completely on RAID that makes efficient use of
disk space.  All the below is via the "expert" partitioning section of the
install (from scratch).

1 - Partition each disk the same.  I used the following scheme for all:
  sd?1:  100MB  (destined to be /boot)
  sd?2:    4GB  (destined to be swap)
  sd?3   290GB  (destined to be root)
(Incidentally, I don't quite see how 320GB drives end up being 290GB in

2 - Instead of formatting these partitions, mark them to be used as RAID
(in the create or edit dialogue, select "do not format" and then "RAID").

3 - Use the drop-down RAID button/menu to join these into three different
RAID devides:
  md0:   100MB RAID 1  /boot  (ext3, mirrored across all disks)
  md1:   3x4GB RAID 5  swap
  md2: 3x290GB RAID 5  /      (ext3)
Note that /boot is RAID 1, which means each disk is the same.  That lets
you bootstrap the system (RAID5 would be unreadable because it's striped).
 This is a waste of space, but it's very small so doesn't matter.  Next,
swap is RAID just so that the system doesn't crash if a disk dies (it
would be faster to have swap without RAID, distributed across all disks). 
Finally, I use a single partition for everything else.  You can, of
course, do something more complex.

Once you do this "everything just works".  The md0... devices "replace"
sda1..., sdb1.. and SuSE does all the right things.  The only difference
from normal is that when it boots you see lots of exciting messages as the
kernel puts everything together.

One final note - it seems that it's best to use SMART for disk monitoring
(or you may not realise when a disk dies).

For the record this was with SuSE 10.2, x86 64bit, and I finally
downloaded the CDs since it was faster overall than repeated experiments
with network install.

Summary: once you work up the courage (and use the RAID button/menu) this
is easy.


How about post-install

From: "andrew cooke" <andrew@...>

Date: Thu, 31 Jul 2008 21:20:48 -0400 (CLT)

---------------------------- Original Message ----------------------------
From:    "Fabian Wein" <fwein@...>
Date:    Thu, July 31, 2008 12:38 pm

How to convert an existing system to a RAID system when the
I get a new (identical) drive?



Re: How about post-install

From: "andrew cooke" <andrew@...>

Date: Thu, 31 Jul 2008 21:23:36 -0400 (CLT)

gah!  i just messed up forwarding this to my blog - i will delete what is
there and the reply, but the simple answer is that i don't know.

i *guess* you might be able to make a system with one disk (ie create a
two disk raid in a broken state) and then copy your data to that.  after
that you could delete the existing data and use that old disk to extend
the array on the new disk.

but this sounds very risky to me.  given the price of disks, i would
suggest buying two, and then once you are sure they are working together,
copy across the data, delete and add the old disk in ("grow").

i am not sure i gave all details on the blog, but at one point i did lose
a system playing around.  i am not 100% confident in the dynamic
modification of the raid, and i am not an expert...

good luck,

Comment on this post