Metadata storage site comparison 1, internalmeta-data (meta-data and data stored on the same underlying device above) benefits: once meta-data created, and the actual data bound together, in the maintenance will be more simple and convenient, there is no need to worry about meta-data will lose because of some action.
In addition to the hard disk is damaged lost data, lost together with meta-data, when replacing a hard drive, simply execute the command to rebuild meta-data, loss of data is very easy to synchronize from another node. Disadvantages: If the underlying device is a single disk, didn't do raid, lvm, or not, it may cause a performance impact. Because every write IO need updated information inside meta-data each time you write IO will have twice, and there will certainly be a head of a larger move because meta-data seek are recorded in the dice equipment end of downtime, write IO performance. 2, externalmetadata (meta-data stored in separate, and storage of data in devices separate from the device above) advantages: disadvantages of relative internalmeta-data completely, you can resolve the issue of contention write IO. Disadvantage: because the data is stored in and meta-data equipment separately, means that when a disk is damaged, replace the disk, you must manually initiate synchronization of whole wheat. Also is to manage the maintenance of slightly cumbersome then little by little, very little. If we want already exists to establish a data device drbd resources above, and do not want to lose the device the above data, and no way to increase the capacity of the underlying device and upper file system and no way to shrink it, we will just have to create the metadata into external mode.
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