实用程序，用于驱动器上的TRIM未分配空间

我有一个带有几个ext4分区的驱动器（SD卡），但是还有一些未分配的空间。该fstrim实用程序只能在文件系统内工作。在我重新发明轮子并写一个轮子之前，是否有另一个实用程序可以对未分配的空间进行修剪（或者可以对明确指定的范围进行修剪）？

我可以确认的是，大部分的设备上未分配的空间是不是目前已知的控制器是免费的，因为我观察到，这种特殊的卡上，读取到修剪空间返回0的，但该设备显示的扫描剩下大量垃圾数据。

编辑：我在使用时遇到问题hdparm。下面的示例舍弃了第一个扇区，但是无论我指定的范围如何，我都会看到相同的结果。fstrim设备上没有任何问题：

root@ubuntu:~# hdparm --please-destroy-my-drive --trim-sector-ranges 0:1 --verbose /dev/mmcblk0 

/dev/mmcblk0:
trimming 1 sectors from 1 ranges
outgoing cdb:  85 0d 06 00 01 00 01 00 00 00 00 00 00 40 06 00
outgoing_data:  
00 00 00 00 00 00 01 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

ioctl(fd,SG_IO): Invalid argument
FAILED: Invalid argument

我正在进一步调查，但是有人有见识吗？

如果您的版本足够新util-linux，则它包含的工具blkdiscard可以使用--offset和--length选项对整个设备或设备范围内的TRIM进行修整。

请注意：这 blkdiscard很危险，如果将其TRIM设置到错误的区域，则数据将丢失！

因此，您可以找出分区表的未分区（空闲）区域，然后使用此工具对它们进行修剪。对于msdos和gpt分区，parted提供如下所示的空闲区域：

# parted -m /dev/sda unit b print free | grep ':free;'
1:17408B:1048575B:1031168B:free;
1:64022904832B:64023240191B:335360B:free;

向其添加循环...

while IFS=: read -ra FREE
do
    echo blkdiscard --offset ${FREE[1]%%B} --length ${FREE[3]%%B} /dev/sda
done < <(parted -m /dev/sda unit b print free | grep ':free;')

哪个打印

blkdiscard --offset 17408 --length 1031168 /dev/sda
blkdiscard --offset 64022904832 --length 335360 /dev/sda

验证此输出对您来说是正确的，如果您喜欢（详细吗？），请添加其他选项，最后删除，echo这样它将被实际执行，并且应该进行设置。

该示例的第二个命令实际上由于长度太小而失败-可能值得在循环内检查，忽略小于1MB的区域，因为它们不太可能成功修剪。

如果使用LVM而不是分区，则可以为空闲空间创建一个LV并进行以下修剪：

lvcreate -l100%FREE -n blkdiscard SSD-VG
blkdiscard -v /dev/SSD-VG/blkdiscard
lvremove SSD-VG/blkdiscard

如果你设置issue_discards = 1你的lvm.conf，你可以跳过blkdiscard为LVM发布有关TRIM呼叫lvremove本身。

hdparm --trim-sector-ranges可以修剪范围。手册页警告使用它，因此您最好确保获得正确的范围和语法。

我认为为分区外部的所有数据发送修剪会很危险，因为那里有时会存在一些隐藏数据，例如引导加载程序代码或第二个分区表。您需要知道一点，分区之外的哪些区域确实未被使用。