How to force a reboot when you have a RAID array attached

When the system gets stuck (yes, this happens in our beloved operating system too) who do you call?

- Sysrq of course!

My usual approach would be:
1) sync all filesystems: alt + sysrq + s (multiple times, the actual value depends on my mood :-)
2) remount all filesystems read-only: alt + sysrq + u
3) cause a reboot: alt + sysrq + b

BUT, this comes with an issue if you're doing software RAID (md).

md devices register themselves (via register_reboot_notifier) to be sync'ed whenever a reboot is about to occur. Also, if the array was being reconstructed (or re-synced) during the reboot operation, you get a nice checkpoint, so that after reboot the operation will continue off from where it left. This is all fine and dandy, but it seems that the sync/checkpointing operation does not occur if you've previously called for an emergency read-only remount of filesystems.

[ It seems that alt + sysrq + u, also makes the raid devices read-only... and thus, not being able to perform any writable operation (such as a sync or checkpoint). BUT, I've yet to find the part of the code that is the cause of this. I'll have another look though, as soon as I figure out what's going on with libata lately. Since 2.6.25 I've been having timeout troubles with my SATA drive (yes, a seagate one). The lkml-suggested 'noncq' option hasn't helped much.. ]

ANYWAY, back to our subject. So you have a raid-array and you want to reboot?
- Just sync (alt + sysrq + s) and reboot (alt + sysrq + b) without doing any RO-remounting.

Read the sign

A message from the (post-Katrina) city of New Orleans to our young vandals in Greece..

Leeching Picassa Albums

Here's a tiny python script for downloading Picassa photo albums!

It requires two parameters: the album's RSS URL (there's
a link to this at the bottom of each album page) and the pathname
of the directory where the downloaded photos will be stored.

Enjoy :-)

#!/usr/bin/env python

import urllib
import feedparser
import sys
import os

if len(sys.argv) != 3 :
   print >> sys.stderr, (("usage: %s " + 
      "<picassa-album-rss> <local-dir>") % sys.argv[0])
   sys.exit(1)

album_rss = sys.argv[1]
local_dir = sys.argv[2]

if not os.access(local_dir, os.W_OK | os.X_OK):
   print >> sys.stderr , ("error: dir %s is not writable" %
                          local_dir)
   sys.exit(1)

abs_dir = os.path.realpath(local_dir)

feed = feedparser.parse(album_rss)

total_items = len(feed.entries)
if total_items == 0:
   print >> sys.stderr , ("error parsing url %s" % album_rss)
   sys.exit(1)

for i in range(total_items):
   # of course this breaks once Picassa change their rss format..
   website = feed.entries[i]["enclosures"][0]["href"]
   slash_pos = website.rindex("/")
   pic_name = website[slash_pos+1:]
   urllib.urlretrieve(website, "%s%s%s" % (abs_dir, os.path.sep,
                                           pic_name))
   print "downloaded: %s (%i/%i)" % (pic_name, i+1, total_items)