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On 06/11/2014 11:34 AM, Stefan G. Weichinger wrote: |
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> Am 11.06.2014 12:14, schrieb thegeezer: |
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> |
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>>> Basically 3 RAID-6 hw-raids over 6 SAS hdds. |
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>> OK so i'm confused again. RAID6 requires minimum of 4 drives. |
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>> if you have 3 raid6's then you would need 12 drives (coffee hasn't quite |
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>> activated in me yet so my maths may not be right) |
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>> or do you have essentially the first part of each of the six drives be |
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>> virtual disk 1, the second part of each of the six drives virtual disk 2 |
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>> and the third part be virtual disk 3 -- if this is the case bear in mind |
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>> that the slowest part of the disk is the end of the disk -- so you are |
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>> essentially hobbling your virtual disk3 but only a little, instead of |
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>> being around 150MB/sec it might run at 80. |
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> |
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> I'd be happy to see 80 ! |
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> |
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> Ran atop now while dd-ing stuff to an external disk and got ~1MB/s for |
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> 2.5GB of data. |
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> |
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> (this is even too slow for USB ...) |
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> |
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> I am unsure what to post here from atop ... ? |
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> |
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> |
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> To the initial question: |
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> |
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> Yes, imagine the six disks "split" or partitioned at the level of the |
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> hardware raid controller (as you described above). |
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> |
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>> you might also like to try a simple test of the following (yes lvs count |
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>> as block devices) |
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>> # hdparm -t /dev/sda |
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>> # hdparm -t /dev/sdb |
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>> # hdparm -t /dev/sdc |
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>> # hdparm -t /dev/vg01/winserver_disk0 |
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>> # hdparm -t /dev/vg01/amhold |
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> everything around 380 MB/s ... only ~350 MB/s for |
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> /dev/vg01/winserver_disk0 (which still is nice) |
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OK here is the clue. |
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if the LVs are also showing such fast speed, then please can you show |
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your command that you are trying to run that is so slow ? |
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