Re: RAID rebuild time and disk utilization....

[Tom Bishop <bishoptf@xxxxxxxxx>]

How do I figure out if it's a 4k sector drive, I've read about that but never looked into it...is there any way to tell, and when you mean start my partition, I only have one large partition, since this is just for my data files....so you mean I should start on 2048 and go up from there???  Thanks in advance...going to do some more reading...


Here is the link to the samsung.... http://www.samsung.com/global/business/hdd/productmodel.do?group=72&type=94&subtype=98&model_cd=507&tab=fea&ppmi=1219

talks about 512B per sector....which would be 4096....unless they changed something...

So should I break it and change the partitions and if so do I do it on both of the disks so they are the same???  Thanks in advance...going to do some more reading...

On Mon, Sep 27, 2010 at 8:54 PM, Ross Walker <rswwalker@xxxxxxxxx> wrote:

On Sep 27, 2010, at 8:16 PM, Tom Bishop <bishoptf@xxxxxxxxx> wrote:

> Here are the iostats:
>
>
> Device:         rrqm/s   wrqm/s   r/s   w/s   rsec/s   wsec/s avgrq-sz avgqu-sz   await  svctm  %util
> sda               0.15     2.47  0.41  0.82    13.01    26.36    31.97     0.01    6.98   1.01   0.12
> sda1              0.02     0.00  0.00  0.00     0.04     0.00    24.50     0.00    5.38   4.82   0.00
> sda2              0.01     0.00  0.00  0.00     0.03     0.00    37.79     0.00    6.77   5.85   0.00
> sda3              0.12     2.47  0.40  0.82    12.93    26.36    31.98     0.01    6.96   1.01   0.12
> sdb               1.48     0.00 315.21  0.01 40533.39     0.75   128.59    26.94   85.45   2.80  88.24
> sdb1              1.47     0.00 315.21  0.01 40533.30     0.75   128.59    26.94   85.45   2.80  88.24

Average queue size of 26.94 requests, average wait time of 85.45ms, service time of 2.8ms ain't bad, but means the sequential IO is randomizing and backing up the IO.

Chances are this is probably a 4k sector drive and the partition's alignment crosses a 4k page causing double reads. Better to start partitions on sector 2048 instead of 63.

Am I correct on these?

If so I'd break the RAID re-partition and resilver it.

-Ross

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