[Date Prev][Date Next] [Thread Prev][Thread Next] [Date Index] [Thread Index]

Re: slow lvm

I hate those. They should just have made it report it's real sector size and wait for controllers and drivers to support it.
Now, you have to make your partitions to start at megabyte boundaries to get full speed, so that the sectors oft the file system come to lie on the physical sectors, or else it will need read out every sector before writing to it. 

Am 11.08.2011 12:50, schrieb Matus UHLAR - fantomas:

On Thursday 11 August 2011 07:48:45 Keith Edmunds wrote:

Do the disks have 1K sectors or 4K sectors?


On 11.08.11 11:37, mimo wrote:

fdisk -l /dev/sdd

hmmm, since when does fdisk show that?



Disk /dev/sdd: 2000.4 GB, 2000398934016 bytes


It's 2T, it should be 4k/sec


Sector size (logical/physical): 512 bytes / 4096 bytes


See? It is...


I/O size (minimum/optimal): 4096 bytes / 4096 bytes


that's why partisions should be rounded on 4K limit.


Device Boot Start End Blocks Id System
/dev/sdd1 * 1 1216 9764864 fd Linux raid autodetect
/dev/sdd2 1216 2432 9765888 fd Linux raid autodetect
/dev/sdd3 2432 8511 48828416 fd Linux raid autodetect
/dev/sdd4 8511 243201 1885151840+ fd Linux raid autodetect


the 'fdisk -lu /dev/sdd' will tell you boundaris on sector range.


fdisk -l /dev/sda

Disk /dev/sda: 2000.4 GB, 2000398934016 bytes
255 heads, 63 sectors/track, 243201 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


This disk tells it has 512B sectors, but that may be just configuration
and reality might be different.
Therefore you could try with 4K rounding too.


Disk identifier: 0x000e0666

Device Boot Start End Blocks Id System
/dev/sda1 * 1 1216 9764864 fd Linux raid autodetect
/dev/sda2 1216 2432 9765888 fd Linux raid autodetect
/dev/sda3 2432 8511 48828416 fd Linux raid autodetect
/dev/sda4 8511 243201 1885151840+ fd Linux raid autodetect
Reply to: