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I recently bought a 1TB Crucial X6 USB portable SSD. I wonder if it is safe to delete the reserved partition of of 128MB (MiB, binary MB). I'm worried that it is reserved as spare sectors/blocks to replace any bad blocks that develop over time, and therefore that deleting the partition and reusing the space will screw up the drive. Would be great of anyone knows exactly what is the purpose of this partition. I have searched extensively for answers already.

Background: I would like to install the Ventoy iso-booting system, which requires free space below 1024kB, and hence conflicts with the reserved partition, as can be seen from the partition table:

gdisk -l /dev/ssd;  shows

Model: Micron CT1000X6SSD9 (scsi)
Disk /dev/sdd: 1000GB
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Disk Flags:


Device      Start        End    Sectors   Size Type
/dev/sdd1      34     262177     262144   128M Microsoft reserved
/dev/sdd2  264192 1953523711 1953259520 931.4G Microsoft basic data


parted /dev/sdd p; shows


Disk /dev/sdd: 931.53 GiB, 1000204886016 bytes, 1953525168 sectors
Disk model: CT1000X6SSD9

Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 4096 bytes / 33553920 bytes
Disklabel type: gpt
Disk identifier: 7810458B-386A-4170-9CF0-07C53C41FB26


Number  Start   End     Size    File system  Name                          Flags
 1      17.4kB  134MB   134MB                Microsoft reserved partition  msftres
 2      135MB   1000GB  1000GB               Basic data partition          msftdata

By the way, I used od -a /dev/sdd1 | more; and od -a -j 127M /dev/sdd1 | tail -100; to confirm that the data in sdd1 is just endless repetitions of ASCII values 0-127. No real data there on a new drive, at least.

Kamil Maciorowski
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reikred
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    That partition is highly recommended, if you delete it, you should recreate it – Ramhound Jan 10 '23 at 22:32
  • Just install Ventoy, it will do what is needed - Microsoft Reserved partitions are not special nor do they serve any useful purpose for your use case – Jaromanda X Jan 10 '23 at 22:38
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    ... despite what many sites say, i.e. things like "MSR MUST be present on all GPT drives" that seems to be completely false. For example, I don't even have MSR on my Windows 11 boot drive, and I installed Windows 11 using Microsoft install media - yes, it's a GPT drive and EFI boot. But as I said above, just install Ventoy, it will do what it needs to – Jaromanda X Jan 10 '23 at 22:53
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    Same experience here. Never actually bumped into any problem in Windows with GPT drive that has no MSR partition. I do wonder if anyone can give a concrete circumstance in which it will be used / repurposed. – Tom Yan Jan 11 '23 at 03:23
  • Funny thing is, while one might argue that it is used as a 128-MiB alignment. Yet at least in the above case, there's a 1-MiB gap between the MSR and the main, which annihilates the argument. (Actually the MSR does not even have 262,144 - 33 - 1 blocks, but 262,144 blocks.) – Tom Yan Jan 11 '23 at 03:25
  • Alright: While none of the above comments address whether the 128MB MSR (Microsoft Reserved) partition is related to spare sectors/blocks or other basic functioning of the SSD, I get the distinct sense that it is NOT and that that it is there as a convention, perhaps to make sure that there will be space available for an EFI partition if one should later be needed for booting. In other words, as an insurance that a naive Windows user does not paint him/herself into a corner by leaving no room up-front. https://superuser.com/questions/942065/is-msr-partition-required-on-secondary-gpt-drives – reikred Jan 11 '23 at 04:16
  • Windows creates this partition automatically on all GPT drives. It is hidden in Windows. Why? No idea. Crucial probably created the default drive contents using Windows. – Daniel B Jul 17 '23 at 13:29

2 Answers2

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I'm worried that it is reserved as spare sectors/blocks to replace any bad blocks that develop over time, and therefore that deleting the partition and reusing the space will screw up the drive.

No, it has got nothing to do with that, such matters are handled by the SSD using overprovisioned, out of LBA user space NAND memory, independently from any partitions and such.

Also, specifically Microsoft creates these partitions which suggests it's a Microsoft Windows specific 'thing'.

Contrary to statements I found with regards to the partition, "For one, the Microsoft Reserved Partition stores the Windows bootloader files." ([example])1), I found it to be completely empty and containing no data what-so-ever.

enter image description here

Joep van Steen
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While none of the comments so far address whether the 128MB MSR (Microsoft Reserved) partition is related to spare sectors/blocks or other basic functioning of the SSD, I get the distinct sense that it is NOT and that that it is there as a convention, perhaps to make sure that there will be space available for an EFI partition if one should later be needed for booting.

In other words, as an insurance that a naive Windows user does not paint him/herself into a corner by leaving no room up-front (or otherwise) for EFI.

I'm making this the official answer for now.

reikred
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