HP-lefthand underlying structure details and storage disaster recovery

HP-lefthand underlying structure details and storage disaster recovery

I. Features of HP-lefthand

HP-lefhand is a very good SAN storage that uses the iSCSI protocol to allocate space for clients. It supports RAID 5, raid 6, and raid 10. It also supports volume snapshots and dynamic volume resizing. Common models include p4500, p4300, and p4000. Based on the disadvantages of market share and software-defined storage, there is a certain data recovery market demand.

The HP-lefhand storage system is an embedded Linux system. You must install the client software before configuring lefthand.

Server:

Customer service end:

Ii. HP-lefthand Storage Structure

Lefthand storage is divided into three levels, which constitute the entire storage. The three levels are as follows:

Physical Disk: the actual physical disk.

Logical Disk: Multiple physical disks constitute a logical disk, that is, raid.

Logical volume: on top of the raid, different raid components form a large space, and different areas in the large space form a volume.

The topology is as follows:

From the topology, we can see that the physical disk must be raid a logical disk, several Logical Disk groups must be created into a large storage space, and the large storage space is divided into several small blocks. The volumes used by the user are composed of several discontinuous small blocks. That is, the user data stored in the volume is eventually divided into several fragments and stored in different logical disks, which are composed of multiple physical disks. The final data is divided into N segments and placed in an inaccessible physical disk.

Volume: the user's available space. As mentioned above, the volume consists of N discontinuous fragments of different raid. The volume stores the file system and user data.

Raid: it consists of multiple physical disks, mostly RAID 5 or raid 6. Raid is the smallest unit that lefthand can recognize. To create a volume, you must first create a raid. Because a volume is composed of N non-consecutive segments of different raid, the raid must record which segment it stores and which segment is the first segment of the volume. Therefore, there is a part of space before raid to store the map that records these fragments.

Physical Disk: all data is recorded in the physical disk, and the data is not consecutive. If the upper layer is RAID 5 or raid 6. The physical disk also contains verification data.

 

Iii. Storage disaster recovery

Through the analysis of lefthand underlying storage, we can clearly know how users' data is stored on the disk. This means that if a storage disaster occurs, we can quickly know where the problem occurs. And make solutions to the problem.

For different storage disasters on lefthand, the corresponding data recovery solution is as follows:

1. When both the physical disk and raid are in good condition, the volume is deleted by mistake. You can retrieve the accidentally deleted Volume Based on the residual map information in the lefthand storage. This module is also available in frombyte recovery for lefthand developed in North Asia. 2. When the physical disk is in good condition and the raid is damaged, a disk in raid may be offline due to too many bad channels, resulting in raid paralysis and volume unavailability. You can recover data through raid reorganization and subsequent activation (backup is required to ensure backtracking of the solution. If the operating system of lefthand cannot be restored, you can also use frombyte recovery for lefthand to explain the volume of the restored raid.

3. When the file system or file in the volume fails, it is not related to lefthand itself, and can be restored directly on the client. We recommend that you add another host to be restored and use iSCSI multipath for read-only connection.

Refer to the following articles:Case Study on storage and data recovery of a court HP-P4500

Deng Qi, North Asia data recovery center Engineer

Email: [email protected]

Phone: 4006505808-801