Re: How to find out data alignment for LVM thin volume brick

[Strahil Nikolov <hunter86_bg@xxxxxxxxx>]

Yes, disk alignment is only needed as the LVM stack cannot get the details of the HW Raids.

In your case , use the default 256k as per documentation.

Best Regards,

Strahil Nikolov 

Sent from Yahoo Mail for iPhone

On Wednesday, June 7, 2023, 9:21 PM, mabi <mabi@xxxxxxxxxxxxx> wrote:

Dear Strahil,

Thank you very much for pointing me to the RedHat documentation. I wasn't aware of it and it is much more detailed. I will have to read it carefully.

Now as I have a single disk (no RAID) based on that documentation I understand that I should use a data alignment value of 256kB.

Best regards,

Mabi

------- Original Message -------
On Wednesday, June 7th, 2023 at 6:56 AM, Strahil Nikolov <hunter86_bg@xxxxxxxxx> wrote:

Have you checked this page: https://access.redhat.com/documentation/en-us/red_hat_gluster_storage/3.5/html/administration_guide/brick_configuration ?

The alignment depends on the HW raid stripe unit size.

Best Regards,

Strahil Nikolov 

On Tue, Jun 6, 2023 at 2:35, mabi

<mabi@xxxxxxxxxxxxx> wrote:

Hello,

I am preparing a brick as LVM thin volume for a test slave node using this documentation: 

https://docs.gluster.org/en/main/Administrator-Guide/formatting-and-mounting-bricks/

but I am confused regarding the right "--dataalignment" option to be used for pvcreate. The documentation mentions the following under point 1:

"Create a physical volume(PV) by using the pvcreate command. For example:

pvcreate --dataalignment 128K /dev/sdb

Here, /dev/sdb is a storage device. Use the correct dataalignment option based on your device.

    Note: The device name and the alignment value will vary based on the device you are using."

As test disk for this brick I have an external USB 500GB SSD disk from Samsung PSSD T7 (https://semiconductor.samsung.com/consumer-storage/portable-ssd/t7/) but my question is where do I find the information on which alignment value I need to use for this specific disk?

Best regards,

Mabi

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