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I am doing a resync on a RAID6 array and I am looking at some 2 days to complete. I looked here for hints on how to speed it up, but I have, instead, managed to slow it down!

HW details are: 10x 4TB WD Black HDDs (one died so resync is due to this) Core2Quad, ASUS P5K Deluxe with 8GB RAM

What are the best params (VALUE) to use for this config and/or how do I calculate these?

Hint 1 - MIN / MAX SPEED LIMITS:

echo VALUE > /proc/sys/dev/raid/speed_limit_min (I set to 90000)
echo VALUE > /proc/sys/dev/raid/speed_limit_max (I set to 900000)

Hint 2 - READ AHEAD:

blockdev --setra VALUE /dev/md0 (set to 32MB / 65536) 

Hint 3: STRIPE-CACHE SIZE (how do I find system_page_size? I set to 32MB / 32768 and have not seen OUT OF MEMORY error):

memory_consumed = system_page_size * nr_disks * stripe_cache_size 
echo VALUE > /sys/block/md0/md/stripe_cache_size 

I have disabled NCQ and enabled internal bitmap before starting resync so these steps are working.

Thanks!

share|improve this question
    
On high spec drives there is no benefit to disabling NCQ –  JamesRyan Mar 17 at 8:25
    
Hi JamesRyan, hmmm the resync increased from 35K to 40K by doing this. It is the rest that has had little effect. Thanks for the reply. –  MarcusL Mar 17 at 9:28
    
That implies that the drive isn't your bottleneck then. –  JamesRyan Mar 17 at 9:52

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