2
I have created RAID1 array of two identical empty partitions.
Now it is saying:
$ tail -f /proc/mdstat
Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10]
md0 : active raid1 sdc1[1] sdb1[0]
3906885440 blocks super 1.2 [2/2] [UU]
[>....................] resync = 1.6% (66113792/3906885440) finish=3821.3min speed=16750K/sec
So it plans to synch for 3 days. Is it normal? What is it actually doing? Calculating proton mass with quantum chromodynamics? Doesn't it see drives are identical?
UPDATE
It was proposed below, that while syncing, RAID1 is just blindly copying one partition onto another. If this true, then why isn't it possible to say it: relax, everything already identical, just mark yourself that data is already copied.
Like in fast formatting.
Is it possible?
1BTW, are you sure you have your partitions properly aligned? If those are 4k drives and you didn't align things you could be be impacting performance a lot. – Zoredache – 2014-10-03T23:13:13.673
Can't imagine what aligning is. Drives are identical and were formatted identically. – Dims – 2014-10-03T23:15:47.917
The drives being identical is irrelevant. Newer drives align to 4k blocks, in the past they aligned to 512 byte blocks. If your partition is aligned improperly then every read and write operation actually involves reading 2 blocks off the hard drive when it should have read one. It makes a huge difference during something like an initial sync of a large RAID1, since a misaligned drive would be doing two times as much work.. See: http://en.wikipedia.org/wiki/Partition_alignment and http://superuser.com/questions/tagged/advanced-format
– Zoredache – 2014-10-03T23:57:46.383BTW just to see, it might be useful if you posted the output of
fdisk -u -l /dev/sdc /dev/sdb
. – Zoredache – 2014-10-04T00:02:58.863