Scheduled Maintenance: We are aware of an issue with Google, AOL, and Yahoo services as email providers which are blocking new registrations. We are trying to fix the issue and we have several internal and external support tickets in process to resolve the issue. Please see: viewtopic.php?t=158230

 

 

 

[Solution not found but problem went away] Single boot: NTLD

Linux Kernel, Network, and Services configuration.
Message
Author
p.H
Global Moderator
Global Moderator
Posts: 3049
Joined: 2017-09-17 07:12
Has thanked: 5 times
Been thanked: 132 times

Re: [Solution not found but problem went away] Single boot:

#21 Post by p.H »

Head_on_a_Stick wrote:Partitioning tools do not delete filesystems or their contents so if a partition is deleted and then re-created the files will still be present.
fdisk from current util-linux offers to erase the filesystem signature when it finds one in a newly created partition. Better give the right answer if you want to keep the data. I would not be surprised if some "smart" partitioning tools erase the existing signature or issue discard/TRIM for the whole partition without even asking when deleting or creating a partition.
Head_on_a_Stick wrote:For solid-state drives blkdiscard(8) is an instantaneous alternative to leaving dd(1) running for hours.
TRIM/discard is not an erase command. It just sends the information that the data are not useful any more and may be erased to the drive controller. Actual erasure may be delayed.

User avatar
Head_on_a_Stick
Posts: 14114
Joined: 2014-06-01 17:46
Location: London, England
Has thanked: 81 times
Been thanked: 132 times

Re: [Solution not found but problem went away] Single boot:

#22 Post by Head_on_a_Stick »

p.H wrote:Actual erasure may be delayed
Well yes but the command is instant and functionally equivalent to a "secure erase" [sic] using hdparm(8).
deadbang

p.H
Global Moderator
Global Moderator
Posts: 3049
Joined: 2017-09-17 07:12
Has thanked: 5 times
Been thanked: 132 times

Re: [Solution not found but problem went away] Single boot:

#23 Post by p.H »

Head_on_a_Stick wrote:the (blkdiscard) command is instant
The goal is to make sure that data are erased, not to return quickly. Some discarded blocks may even never be erased, for exemple if the controller stops garbage collection and block erasure when the free block count exceeds a threshold.
Head_on_a_Stick wrote:and functionally equivalent to a "secure erase" [sic] using hdparm(8).
Source ?

User avatar
Head_on_a_Stick
Posts: 14114
Joined: 2014-06-01 17:46
Location: London, England
Has thanked: 81 times
Been thanked: 132 times

Re: [Solution not found but problem went away] Single boot:

#24 Post by Head_on_a_Stick »

p.H wrote:The goal is to make sure that data are erased
There is only one way to make sure that all data is erased on a solid-state device: https://www.youtube.com/watch?v=sQYPCPB1g3o
p.H wrote:
Head_on_a_Stick wrote:and functionally equivalent to a "secure erase" [sic] using hdparm(8).
Source ?
See https://linux-ide.vger.kernel.narkive.c ... sing-a-ssd

The two commands call different ATA functions but both attempt to erase all data on the drive.
deadbang

p.H
Global Moderator
Global Moderator
Posts: 3049
Joined: 2017-09-17 07:12
Has thanked: 5 times
Been thanked: 132 times

Re: [Solution not found but problem went away] Single boot:

#25 Post by p.H »

Head_on_a_Stick wrote:There is only one way to make sure that all data is erased on a solid-state device: https://www.youtube.com/watch?v=sQYPCPB1g3o
Can you please provide a short description for those like me who cannot or do not want to view videos from youtube ?
Is it about something else than physical destruction ?
Head_on_a_Stick wrote:See https://linux-ide.vger.kernel.narkive.c ... sing-a-ssd

The two commands call different ATA functions but both attempt to erase all data on the drive.
The reply states otherwise : what these two functions actually do is firmware-dependent. Also, the thread was focused on speed, not security.
When you use blkdiscard, the SSD (assuming a SATA SSD) will receive an
ATA TRIM command, whereas hdparm --security-erase will issue an ATA
SECURITY ERASE UNIT command.

What the drive then actually does is dependant on the implementation
details of that particular SSD's firmware.

In general, I would expect the performance gain from TRIMing the entire
drive to be either the same-as, or possibly less-than the gain from
SECURITY ERASE. For a sane firmware implementation I'd expect them to
have the same effect on performance. Firmware implementations are not
always sane.

User avatar
Head_on_a_Stick
Posts: 14114
Joined: 2014-06-01 17:46
Location: London, England
Has thanked: 81 times
Been thanked: 132 times

Re: [Solution not found but problem went away] Single boot:

#26 Post by Head_on_a_Stick »

p.H wrote:Can you please provide a short description for those like me who cannot or do not want to view videos from youtube ?
Oh, sorry. Better link: https://patents.google.com/patent/US20170050190A1/en
p.H wrote:Is it about something else than physical destruction ?
No.

The dd command is no more guaranteed to clear the contents of the drive than either hdparm or blkdiscard because of over-provisioning. Physical destruction is the only way to be sure.
deadbang

Post Reply