Application Research Of LVM Snapshot Under The Environment Of Linux

With the development of information technology, the base of information-data hasincreasingly become the core of an enterprise. Loss of data will cause a fatal strike tothe enterprise. Data security is particularly important for an enterprise. The mosteffective means to prevent data loss is data backup. The backup data must be ensured itsconsistency. During the backup, the original data can’t be changed. Otherwise, thebackup data are almost no sense. In order to ensuring the consistency of backup data,the general way is to set data to be read-only, and then back up the data, this way willseriously affect the company’s business. Using Linux snapshot technology can get aconsistent backup data, within a very short time, which almost does not affect the upperlayer application. Linux snapshot technology tend to be designed as one original volumecorresponds to one snapshot volume, when need multiple snapshots, each snapshotvolume will be dealt independently. In this way, before writing date to the originalvolume, it need to update the data blocks in some or even all of the correspondingsnapshot volumes, which will increase the storage space consumption, and lower writeperformance of the original volume.Based on the Linux source code, to overcome the disadvantage of Linux snapshotthat snapshot volume storage efficiency is low and write performance of originalvolume is poor in application of multi snapshot volumes, I have designed and realizedthe same-origin snapshot iteration storage, which utilizes the correlation of snapshotvolume data, re-organizes storage structure, reduces the storage space consumption ofthe snapshot volume and dramatically improves the write performance of the originalvolume. However, the improved algorithm increased the correlation between thesnapshot volumes, when a snapshot volume is failure, associated with the snapshotvolume is also invalid, which will reduce the security of data. For the problem, I designand realize the automatic alarm function which will alarm when snapshot volumecapacity is low, as well as arrangements the system running on RAID5. The formerdesign, the capacity of the snapshot volume below a threshold will alarm to alert theadministrator using the LVM expansion capabilities command to expand the capacity of the snapshot volume, which is an effective way to avoid the snapshot volume spacedepletion and which will lead the snapshot volume invalid. The RAID5improves theperformance of read and write and, more importantly, provides a tolerance functionwhich can recover data in the event of a physical failure of a disk. Both of them caneffectively make up the problems of security reduce which caused by the storagemethod of the improved snapshot volumes.Using a detailed test program to test the entire system, the test results show that thespeed of disk I/O has increased and the system has a function of fault-tolerant. Whencreating more than one snapshot volumes on one original volume, it can reduce thestorage space consumption and improve the performance of writing original volume. Inextreme cases, when creating5snapshot volumes on one original volume, writeperformance of the original volume can be increased to2.59times. When the capacityof the snapshot volume is low, the automatic alarm function can remind theadministrator to expand capacity of the snapshot volume, avoid the snapshot volumestorage space is exhausted which will lead snapshot failed.