On 2010-11-15 00:13, Neil Brown wrote:
Depending on which version of mdadm you are using, the default chunk size will be 64K or 512K. I would recommend using 512K even if you have an older mdadm. 64K appears to be too small for modern hardware, particularly if you are storing large files.
root@gs0:/home/geograph# mdadm -V mdadm - v2.6.7.1 - 15th October 2008 root@gs0:/home/geograph# This was what apt-get install got for me, from Ubuntu 10.04 64bit Desktop. Should I download & compile a newer one? (Where from? - haven't found the mdadm developer page yet))
For raid6 with the current implementation it is safe to use "--assume-clean"
Is my above version "current" enough?
to avoid the long recovery time. It is certainly safe to use that if you want to build a test array, do some performance measurement, and then scrap it and try again. If some time later you want to be sure that the array is entirely in sync you can echo repair> /sys/block/md0/md/sync_action and wait a while. I agree with what Mikael and Luca suggested - particularly the suggested for "--bitmap internal". You really want that. N
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