[linux-lvm] Filesystem corruption with LVM's pvmove onto a PV with a larger physical block size
ifranzki at linux.ibm.com
Thu Feb 28 10:10:27 UTC 2019
On 28.02.2019 10:48, Ilia Zykov wrote:
>> Well, there are the following 2 commands:
>> Get physical block size:
>> blockdev --getpbsz <device>
>> Get logical block size:
>> blockdev --getbsz <device>
>> Filesystems seem to care about the physical block size only, not the logical block size.
>> So as soon as you have PVs with different physical block sizes (as reported by blockdev --getpbsz) I would be very careful...
> Hello everybody.
> Maybe, I don’t understand what do you mean. What the logical block size
> mean? But on my machines(CentOS7), this utility get me the strange
> results (output reduced):
> smartctl -i /dev/sda; blockdev --getbsz --getpbsz /dev/sda
> Device Model: INTEL SSDSC2KB480G8
> User Capacity: 480,103,981,056 bytes [480 GB]
> Sector Sizes: 512 bytes logical, 4096 bytes physical
> Rotation Rate: Solid State Device
> smartctl -i /dev/sdb; blockdev --getbsz --getpbsz /dev/sdb
> Device Model: HGST HUS722T2TALA604
> User Capacity: 2,000,398,934,016 bytes [2.00 TB]
> Sector Size: 512 bytes logical/physical
> Rotation Rate: 7200 rpm
> Form Factor: 3.5 inches
> As you see “–getbsz” forever 4096.
I also see logical block size to be 4096 for all devices on my system.
> But I think it must be forever 512.
> What does it mean?
I have seen the following description about logical and physical block sizes somewhere in the internet:
"Logical block sizes are the units used by the 'kernel' for read/write operations.
Physical block sizes are the units which 'disk controllers' use for read/write operations."
For the problem mentioned in this thread, the physical block size is what you are looking for.
> Thank you.
eMail: ifranzki at linux.ibm.com
Tel: ++49 (0)7031-16-4648
Fax: ++49 (0)7031-16-3456
Linux on IBM Z Development, Schoenaicher Str. 220, 71032 Boeblingen, Germany
IBM Deutschland Research & Development GmbH / Vorsitzender des Aufsichtsrats: Matthias Hartmann
Geschäftsführung: Dirk Wittkopp
Sitz der Gesellschaft: Böblingen / Registergericht: Amtsgericht Stuttgart, HRB 243294
IBM DATA Privacy Statement: https://www.ibm.com/privacy/us/en/
More information about the linux-lvm