执行低级格式化后数据居然没丢?

[ChaosAttractor]

将一块 SAS 的希捷 EXOS 10T 从 512e 低级格式化到了 4Kn ，具体来说更新固件后执行了

openSeaChest_Format -d /dev/sg1 --formatUnit 4096 --fastFormat 1 --poll --confirm

使用的是 fastFormat

结果格式化完重新插拔后发现居然还能 mount ，从备份里验证了一下哈希居然一个不差

这合理吗?

[sNullp]

合理，你进行的创造根本不是低格。

[ChaosAttractor]

@sNullp
```
--fastFormat [fast format mode] (SAS Only) (SBC4 required)
Use this option with the --formatUnit option
to run a fast format.
Changing sector sizes is intended for supported Seagate products
used in some hardware RAID configurations. Please consult your
hardware RAID documentation for information about compatibility and
using 4K native sectors before using this option!
Software RAID or individual/JBOD drive solutions will see no benefit as modern
file systems and modern operating systems are already 4K aware even on
512 emulation drives. Modern operating systems already align file systems to 4K
boundaries required by these drives for optimal performance.
Performing a sector size change is data destructive and has a risk that
the adapter, driver, or operating system may not know how to communicate with
the device once this has completed.
There is an additional risk when performing a low-level fast format that may
make the drive inoperable if it is reset at any time while it is formatting.
Available fast format modes:
0 - This is a standard format unit command. All logical
blocks will be overwritten. This command will take a
very long time
1 - This is a fast format unit command keeping existing
data in physical sector. This option can be used to
quickly change the the logical sector size between
5xxe and 4xxx. The media may be readable, but data
may be unspecified or may return errors on read access
according to it's error processing algorithms.
2 - This is a fast format unit command that can change the
logical sector size quickly. Media may or may not be
read accessible until a write has been performed to
the media.

WARNING: Any interruption to the device while it is formatting may render the
drive inoperable! Use this at your own risk!
WARNING: Set sector size may affect all LUNs/namespaces for devices
with multiple logical units or namespaces.
WARNING: Disable any out-of-band management systems/services/daemons
before using this option. Interruptions can be caused by these
and may prevent completion of a sector size change.
WARNING: It is recommended that this operation is done from a bootable environment
(Live USB) to reduce the risk of OS background activities running and
triggering a device reset while reformating the drive.
```
这是 fastFormat 的注释，的确 fastFormat 没有执行清除，但看起来能够完全保留数据也不是期待的结构

[sNullp]

@ChaosAttractor 如果是 lba addressing 改 sector size 不会有任何影响，而现在没什么程序还在用 sector addressing 了。总而言之这和低格没关系。

[Ipsum]

Fastfomat 不会用 0 填充，只是把 metadata 删了而已。

[xiao9469]

有一种方法可以判断有没有用 0 覆盖，你看执行的总时长就知道了。300MB 每秒的写入速度，你写完 10TB 的 0 ，总共需要 9.7 个小时。如果你 10 秒就格完了这个硬盘，那数据肯定还在

[Hookery]

看名字是 fastformat 啊。。。

[chengyiqun]

执行 fastFormat 就不可能是低格了