Speed very slow when resync hard disk with mdadm server fault. How to increase speed of software raid rebuilding in linux written by rahul, updated on july 21, 2014. Increase the speed of linux software raid reconstruction mdblog. Speed up linux software raid various command line tips to increase the speed of linux software raid 015610 reconstruction and rebuild. As for raid 6, it takes much more time to rebuild the array after a disk failure, because it needs to calculate parity. Helpful tips to speed up a linux sofware raid rebuild.
Writes hang out around 23rds of the total write speed for all drives, making this the powerusers option. But think about if you are running a high storage capacity server or any backup drives. The raid can be implemented either using a special controller hardware raid, or by an operating system driver software raid. Helpful tips to speed up a linux sofware raid rebuild the daily. When disk failures occur, you should replace disk and rebuild the raid. Why speed up linux software raid rebuilding and resyncing. As we can see that maximum speed looks fine, but minimum speed is low, which we need to increase. The following hacks are used for recovering linux software raid, and to increase the speed of raid rebuilds. Next, i type the command cat procmdstat and it reported that md0 is active and recovery is in progress.
It should be noted that i had to specify a custom disk policy for this raid 5 volume to enable write caching. Windows 10 has made it simple to set up raid by building on the good work of windows 8 and storage spaces, a software application built into windows that takes care of configuring raid drives for you. As expected from hardware raid 5, we receive roughly 100% read speed from all drives, for some truly mammoth read speeds. If you want the best possible performance, give up on the idea of using software raid. Recently, i build a small nas server running linux for one my client with 5 x 2tb disks in raid 6 configuration for all in one backup server for linux, mac os x, and windows xpvista710 client computers.
In that time when any raid disk failed and we replaced it with a new disk. As per above output i found that raid reconstruction speed is set minimum to kbsecdisc and maximum to 200000 kbsecdisc. No matter if you use hardware or software based raid, the processor must read the contents of all drives simultaneously and use that. The speed is in kibibytes per second 1 kibibyte 2 10 bytes 1024 bytes, and is a perdevice rate, not a perarray rate. For raid 10, its rebuild speed is faster, because it only has to copy from the surviving mirror to rebuild a drive. The first 3 tips can be used even after the rebuild. Increase the speed of linux software raid reconstruction. Options are good for tweaking rebuilt process and may increase overall system load, high cpu and memory usage.
Raid stands for redundant array of inexpensive disks. While we are learning about raid devices, generally we used smaller disks to build a raid array. It is a way to virtualize multiple, independent hard disk drives into one or more arrays to improve performance, capacity and reliability. Then raid rebuilding takes a few minutes or seconds only. There is an option to enable or disable this feature while running mkfs. My experience with software raid has been that its slower than hardware raid. This makes sense when you stop and think about the fact that software is another layer the data has to go through a layer that requires cpu cycles. How to increase speed of software raid rebuilding in linux. If you are in a situation where you sit in front of the console or on a remote ssh connection waiting for a linux software raid to finish rebuilding either you added a new drive, or you replaced a failed one, etc. In the examples, i use devmd0 as the raid array, youll have to change this to your array name. Bite the bullet and invest in a good raid card and good drives to go with it. Before setting any speed make sure that you are enough cpu and ram resources. Improving the speed of software raid on linux readwriteresync.