Cinder

Anyway to avoid filling zero when deleting a volume?

Asked by Lingfeng Xiong

Hi all,
I found when I deleting a volume, cinder will fill the whole volume with zero. This may cause two problem:
1. it waste a lot of time
2. it often failed in my servers

I don't know why but it always failed in my server, even with a brand new hard driver. When it failed, my volume will be leave at a "Error_Deleting" state and I cannot delete it completely.
I know this is good for security, but I really think I don't need it.
Anyway to turn it of?
Thanks in advanced.

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Lingfeng Xiong (xionglingfeng) said : 		#1

Ok... since no one give me a hand, I will answer this question by myself...

For some server, like mine, always crash when deleting a volume because it executed some operations like
dd if=/dev/zero of=XXXX

This operating could took a long time and make server load extremely high, furthermore, it may crash some servers like ours. And when this operation failed, the volume will leave at 'Error_deleting' status, neither can be deleted nor be restored to 'Available' status.

To zero out a volume before deleting it is a good strategy for security. However, for some secure insensitive private cloud system like ours, this is unnecessary. So here's the solution to avoid zeroing out a volume before deleting it:
Use a editor to open /usr/lib/python2.7/dist-packages/cinder/volume/driver.py
Go to line 160 (I have patched cinder to support O_DIRECT on virtual driver, so the line number in vanilla Folsom cinder package should be a bit smaller than this.)
This line should be
self._copy_volume('/dev/zero', self.local_path(volume), size_in_g)
the first line of function _delete_volume()
Just comment that line out.

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Avishay Traeger (avishay-il) said : 		#2

That will indeed fix it, but a better way is to set the "secure_delete" flag to False.

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Lingfeng Xiong (xionglingfeng) said : 		#3

Hi Avishay,
Could you explain a bit more future? Where to set that flag?

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Avishay Traeger (avishay-il) said : 		#4

In cinder.conf, add the following line:
secure_delete = False

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