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Top Forums UNIX for Dummies Questions & Answers Difference between buffered disk reads and cached reads? Post 302538491 by pinga123 on Wednesday 13th of July 2011 06:23:02 AM
Old 07-13-2011
Difference between buffered disk reads and cached reads?

I was analyzing the Disk read using hdparm utility.

This is what i got as a result.

Code:
# hdparm -t /dev/sda

/dev/sda:
 Timing buffered disk reads:  108 MB in  3.04 seconds =  35.51 MB/sec

Code:
# hdparm -T /dev/sda

/dev/sda:
 Timing cached reads:   3496 MB in  1.99 seconds = 1756.56 MB/sec

I m not sure what does Cache read and buffered disk read mean.

Please share your hdparm output for comparison purpose.
 

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PVCK(8) 						      System Manager's Manual							   PVCK(8)

NAME
pvck - check physical volume metadata SYNOPSIS
pvck [-d|--debug] [-h|--help] [-v|--verbose] [--labelsector] PhysicalVolume [PhysicalVolume...] DESCRIPTION
pvck checks physical volume LVM metadata for consistency. OPTIONS
See lvm for common options. --labelsector sector By default, 4 sectors of PhysicalVolume are scanned for an LVM label, starting at sector 0. This parameter allows you to specify a different starting sector for the scan and is useful for recovery situations. For example, suppose the partition table is corrupted or lost on /dev/sda, but you suspect there was an LVM partition at approximately 100 MB. This area of the disk may be scanned by using the --labelsector parameter with a value of 204800 (100 * 1024 * 1024 / 512 = 204800): pvck --labelsector 204800 /dev/sda Note that a script can be used with --labelsector to automate the process of finding LVM labels. SEE ALSO
lvm(8), pvcreate(8), pvscan(8) vgck(8) Sistina Software UK LVM TOOLS 2.02.95(2) (2012-03-06) PVCK(8)
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