Adaptec controllers can take forever to initialize. LSI controllers are instantaneous, or at least they used to be. I haven't used one in a while. Posted by: mattkime. Posted by: microchip The act of being secure is entirely different. I may buy one by the end of the year but I'm not interested in being an early adopter. Posted by: ztirffritz. I have two identical Dell Servers with 6 drives.
It took about 2 hours to initialize them. Quote mattkime another reason why RAID isn't a cure all storage solution. Is this a betting pool? I'll bet 19 hours. Posted by: Mr If it's offline until it's finished it should be quicker, much quicker. So that's c. Sorry, only registered users may post in this forum.
Click here to login. If, OTOH, one of the hard drives will simply report "I cannot read that block", which is more probable with a failing drive, you just have detected a failure early, and reduced time you're running in degraded mode counting from the drive failure, not from when you notice it.
Raid won't help you if one drive fails and a month later the other one fails if you don't notice the first failure in that month. Now, for RAID10 all of the above holds. This is all undefined behavour. The question is, on which disk in each mirror is the data valid? In a freshly created array, this cannot be known, as the disks may have different data. Remember also that RAID operates at a very low level; it knows nothing of filesystems or whatever data might be stored on the disk.
There might not even be a filesystem in use. Thus, initialization in these arrays consists of the data from one disk in each mirror being copied as-is to the other disk. This also means that the array is safe to use from the moment of creation, and can be initialized in the background; most RAID controllers and Linux mdraid have an option for this, or do it automatically. Simply put because two new disks are not expected to be mirror perfect copies of each other from the onset.
In addition initialization includes setting up the metadata superblock with information about the array configuration as well. So, your system should still be responsive, although your disk LEDs will also be showing lots of activity.
The reconstruction process is transparent, so you can actually use the device even though the mirror is currently under reconstruction. First create an ordinary linear non-RAID filesystem and load it with your data. Then convert it to a RAID filesystem with lvconvert. This is better than first copying every block from one uninitialized device to another and then writing your data to both devices.
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Why does a raid 10 device need to be initialized? Ask Question. Asked 5 years, 9 months ago. Active 1 year, 2 months ago. Viewed 5k times. Is it just so people feel better about it? Improve this question. Michael Graff Michael Graff 6, 1 1 gold badge 23 23 silver badges 36 36 bronze badges. Good question. It is possible to skip the synchronization when the RAID is being created, and I have come across recommendations for doing so in case one or more underlying devices are SSD.
I don't know if scenarios exist in which the synchronization is needed for correct operation. Add a comment. Active Oldest Votes. And you should be doing periodic checks. Improve this answer. Simon Richter Simon Richter 2, 15 15 silver badges 17 17 bronze badges.
I can see why periodic checks for readability of data can be useful. But what good does a periodic check for the replicas being identical do? Such checks can be useful if performed by a file system which checksums data.
Please do not enter contact information. If you require a response, contact support. Safari Chrome Edge Firefox. Support Navigation Support. Close Window. Such a disk change notification can be the result of hard drive failure, or one or two of the RAID drives going offline, depending on the RAID configuration. Before deciding to initialize the existing RAID array, please take a moment to consider the consequences.
If you decide to initialize you will lose all existing data on the RAID array. It may be prudent to try other steps first to repair the failed array. Check on the Tested Hardware and Operating System list which firmware the hard drive was validated with by Intel.
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