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# Preventing etxternal usb 3 hard disk from going to sleep

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I have an Toshiba store.e external USB 3 harddisk, that goes to sleep after a while, basically dissappearing from my ubuntu machine. How can I prevent that?

The above problem has been annoying me for a while. Its preventing me to do a copy of my main backup harddisk.

I have two approaches underway atm. One is

sudo sdparm --clear STANDBY -6 /dev/sde

the other is a little python script that will keep the disk busy in a given interval.

#!/usr/bin/python
import os, sys, random,time
if len(sys.argv) != 3:
print 'usage:\n   %s path interval' % sys.argv[0]
sys.exit()
path = sys.argv[1]
interval = sys.argv[2]

prefix = 'prevent_standby_'

while 1:
#delete old ones
oldnames = [n for n in os.listdir(path) if n.startswith(prefix)]
for name in oldnames:
oldpath = os.path.join(path,name)
print 'deleted '+oldpath
print
#write new
suffix = random.randint(1000000,9999999)
newname = os.path.join(path,prefix+str(suffix))
content = 'foo %s' % random.randint(1000000,9999999)
fh = open(newname,'w')
fh.write(content)
fh.close()
print 'wrote   '+newname
os.system('sync')
time.sleep(int(interval))

Lets wait to see which one actually works

Ok, at least one combination does work: the script above and disabling power management by doing:

sudo hdparm -B 255 /dev/sde

On the one side this shows the harddisk to be somewhat unusable - but just doing a copy of another hd, and storing this hd somewhere offline, its good enough.