Different block sizes for partition and underlying logical disk on HP Raid Controller (Linux)

Posted by Wawrzek on Server Fault See other posts from Server Fault or by Wawrzek
Published on 2012-09-18T11:41:47Z Indexed on 2012/09/27 3:39 UTC
Read the original article Hit count: 486

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linux

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Performance

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raid

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hp

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io

Following links collected in this thread I started to check blockdev and found the following output indicating different sizes for partition c0d9p1 and the underlying device (c0d9):

[root@machine ~]# blockdev --report /dev/cciss/c0d9
RO    RA   SSZ   BSZ   StartSec     Size    Device
rw   256   512  4096          0 3906963632  /dev/cciss/c0d9
[root@machine ~]# blockdev --report /dev/cciss/c0d9p1 
RO    RA   SSZ   BSZ   StartSec     Size    Device
rw   256   512  2048          1 3906959039  /dev/cciss/c0d9p1

We have a lot of small files, so yes the block size is smaller than normal. The device is a logical driver on an HP P410 raid controller, simple disk without any raid - RAID 0 on one disk to be precise. (Please note that above configuration is a feature not a bug).

Therefore, I have the following questions.

Can the above discrepancy in the block size affect disk performance?
Can I control the block size using hpacucli?

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