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From: =?UTF-8?Q?Bj=C3=B6rn_Lundin?= <bnl@nowhere.com>
Newsgroups: comp.sys.raspberry-pi
Subject: Re: Move bookworm system from SSD to NVME
Date: Sat, 3 Aug 2024 00:08:00 +0200
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On 2024-08-02 16:12, The Natural Philosopher wrote:
> On 02/08/2024 15:03, Björn Lundin wrote:
>> On 2024-08-02 14:51, The Natural Philosopher wrote:
>>
>>> Never mind sync.
>>>
>>> It's important to wait anyway on an SSD/nvm until it has finished its 
>>> internal business.
>>>
>>> For any copy process.
>>
>>
>> dd'ing 500 Gb to an ssd disk, I've seen sync taking 30 s or more
>> and sync is of course started AFTER dd is done
>>
>> So - how do you know it is done its internal business?
>> Not all drives have blinking LEDs
>>
>> sync makes it easy to know
>>
>>
> Even sync may not be enough.
> SSDS/NVM have their own internal  caching.
> 

Then the question remains - how do you know when its done?

from man sync you get
"sync - Synchronize cached writes to persistent storage"

In other words, doing sync at least clear the cache,
which must be better than nothing? or?

Or are you saying that ripping the power to a newly sync()ed disk may 
mess it up?

as in

dd ....
sync
rip out usb cord for a 2.5" ssd sata in a usb case or something similar ?


-- 
/Björn