Cho mình hỏi tí,

Ai cũng biết feature LVM là Logical Volume Manager cho Linux và Windows dùng để quản lý đĩa dễ dàng hơn trong việc lưu trữ dữ liệu

Khi kết hợp nhiều ổ cứng với nhau để tạo thành Volume, và khi ghi dữ liệu xuống đĩa, thì dữ liệu sẽ ghi lần lượt hết đĩa Hdd này sang đĩa Hdd kia cho đến HDD thứ N.

và đến khi dung lượng HDD x còn dư 2M, ta muốn chép file 10M lên, thì file 10M này sẽ ghi 2M trên Hdd x và 8M còn lại trên HDD (x+1) hay ghi hẳn 10M lên Hdd (x+1) luôn ?

thanks
 

Tớ đoán là trường hợp 1 (nó ghi 2M lên hdd (x) và 8M lên hdd (x+1))

Liên quan đến vụ LVM này, Unix và Linux lại đặt tên khác nhau:
- Trên Unix, PV chia thành các PPs (Physical Partitions), LV chia thành các LPs (Logical Partitions)
- Còn trên Linux, PV chia thành các PEs (Physical Extents), LV chia thành các LEs (Logical Extents) 

Dù các HDD kết hợp lại với nhau, nhưng nó vẫn là các HDD khác nhau, vậy với các file nén như exe, zip, tar... thì theo anh nó sẽ được ghi như thế nào trong trường hợp này. 

Metadevice :A virtual device composed of several physical devices - slices/disks . All the operations are carried out using metadevice name and transparently implemented on the individual device.
RAID : A group of disks used for creating a virtual volume is called array and depending on disk/slice arrangement these are called various types of RAID (Redundant Array of Independent Disk ).
RAID 0 Concatenation/Striping
RAID 1 Mirroring
RAID 5 Striped array with rotating parity.
Concatenation :Concatenation is joining of two or more disk slices to add up the disk space . Concatenation is serial in nature i.e. sequential data operation are performed serially on first disk then second disk and so on . Due to serial nature new slices can be added up without having to take the backup of entire concatenated volume ,adding slice and restoring backup .

Striping :Spreading of data over multiple disk drives mainly to enhance the performance by distributing data in alternating chunks - 16 k interleave across the stripes . Sequential data operations are performed in parallel on all the stripes by reading/writing 16k data blocks alternatively form the disk stripes.

Mirroring : Mirroring provides data redundancy by simultaneously writing data on to two sub mirrors of a mirrored device . A submirror can be a stripe or concatenated volume and a mirror can have three mirrors . Main concern here is that a mirror needs as much as the volume to be mirrored.

RAID 5 : RAID 5 provides data redundancy and advantage of striping and uses less space than mirroring . A RAID 5 is made up of at least three disk which are striped with parity information written alternately on all the disks . In case of a single disk failure the data can be rebuild using the parity information from the remaining disks .
 

For example, multiple PVs can be connected together to create a single large logical volume as shown in Figure 3. LVM linear mapping. This approach, known as a linear mapping, allows a file system or database larger than a single volume to be created using two physical disks. An alternative approach is a striped mapping, in which stripes (groups of contiguous physical extents) from alternate PVs are mapped to a single LV, as shown in Figure 4. LVM striped mapping. The striped mapping allows a single logical volume to nearly achieve the combined performance of two PVs and is used quite often to achieve high-bandwidth disk transfers.