Question What does Windows change when you connect a drive differently?

dstansberry

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Mar 4, 2019
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This may be a odd sort of topic, but I hope someone brighter than me can shed some light.

I have a Synology NAS, which had 5x2TB hard drives. I needed to increase the storage capacity, so I replaced the drives with 4TB models.
Before doing so, I wanted to back up the data the NAS contained, so I took a brand new 4TB drive, inserted it into a USB dock (or cradle). I initialized it GPT, formatted it NTFS, and connected it to the NAS.

The NAS recognized the drive as usable, and I backed up 3.6TB of data onto the drive. Before replacing the NAS drives, I wanted to verify the contents of the backup, so I connected the drive to a nearby Windows PC - but didn't use the USB dock. Instead, I connected the drive to an eSATA port on the PC and verified the data was complete and intact.

I replaced the drives in the NAS, waited for the re-installation of the DSM software to complete, then reconnected the drive in the USB cradle, only to find the NAS declared it to now be in an unsupported format. Connected to Windows, via eSATA or the USB dock, the data is still present and intact.

As an expirement, I did the same thing again with a different drive. GPT/NTFS, visible and usable to the NAS. I Copied a file, then disconnected and reconnected to the eSATA port. Once the drive was connected via eSATA, it, too, became unusable due to an unsupported format.

It seem clear, in my mind, that Windows affects some kind of structural change when the drive is connected via USB vs eSATA (and, presumable SATA as well). I was wondering if that is true, and if so, what is it doing?
 

USAFRet

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Mar 16, 2013
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NAS vs Windows is completely different.

In the NAS, what type of formatting/configuration was this volume?
JBOD, RAID<something>....
NTFS, ext4, other...

Your Synology is Linux based, your PC is Windows based.
You can't just move the physical drive back and forth.
Given correct formatting and connection, you CAN copy data back and forth.
 

dstansberry

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Mar 4, 2019
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Thank you for your reply!

I wasn't attempting to move the drives back and forth, really. I simply connected the drive that I had initialized and formatted in Windows using a USB dock to the USB port in the NAS, where it worked.

I reconnected the drive to the same Windows PC, but this time, I didn't use the USB dock - I used an eSATA cable. I simply read the drive to be sure the data was there, then disconnected the drive. Windows had no issue reading the drive at all, but it appears to have changed the format of the drive in such a way as to make it unusable to the NAS.

In other words, Windows appears to modify the format of USB drive when it's connected to eSATA. I was inquiring as to what changes it makes, and why. Windows still recognizes the partition as NTFS (a format the NAS supports), but the NAS no longer recognizes the format, even though it originally recognized it after Windows formatted it in the first place.

I hope that... clarifies? things. It's not hugely important - the data is safe, I can transfer it over the network, no harm no foul. But what did Windows do to the drive that rendered it unusable to the NAS just by plugging it in differently?
 

dstansberry

Prominent
Mar 4, 2019
9
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NAS vs Windows is completely different.

In the NAS, what type of formatting/configuration was this volume?
JBOD, RAID<something>....
NTFS, ext4, other...

Your Synology is Linux based, your PC is Windows based.
You can't just move the physical drive back and forth.
Given correct formatting and connection, you CAN copy data back and forth.

I'm sorry - I missed your questions!
Originally, the NAS consisted of 5 drives, formatted btrfs, in an SHR1 configuration.
The windows-formatted drive was GPT/NTFS.
I connected the windows-formatted drive to the NAS via USB and backed up the data. I never formatted the drive via the NAS. It was simply plug and play.
I connected the windows-formatted drive back to the Windows PC it was formatted in - but I used a different connection type (eSATA rather than USB). I did not format the drive, or make an changes to it at all. I simply plugged it in and verified the data.

Later, I replaces the drives in the NAS and reinstalled the DSM. This time, I used EXT4 and SHR1. When I connected the same windows-formatted drive to the USB port on the NAS, it could no longer read the NTF partition. Windows appeared to have modified it in some way, simply by my having connected it via eSATA.

At first, I thought perhaps I had done something wrong - perhaps my choosing the ext4 instead of brtfs caused the DSM to not be able to read the drive, so I conducted a test. I took another drive and connected it to Windows via USB. I formatted it GPT / NTFS, and connected it to the NAS via USB. It was identified and accessible. I copied a single file over.

I connected it to windows via USB and read the data. The NAS was also able to read the data. I returned it to Windows and connected it via eSATA. That's all. Just connected it. Afterwards, the NAS was no longer able to use the drive via USB. Windows appears to have changed the drive format.
 

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