Hello,

Multiattach is on the block level, think of it as connecting the same physical harddrive to two computers, but you can compare it to iSCSI in this case.
You must still solve the filesystem issue by using a clustered filesystem on top of the attached volumes [1] and ext4 and xfs is not one of them.

Best regards

[1] https://en.wikipedia.org/wiki/Clustered_file_system

On 22 Jan 2024, at 09:05, Shubham Kumar Yadav <shubham.kumar.yadav369@gmail.com> wrote:

Hi, i have a question/issue related to multiattach feature in cinder
 
i have an openstack cluster and i have configured multiattach in the openstack cinder now when i create 1 volume (with volume type multiattach) and attach it to 2 instances test1 and test2
on test1 
sudo mkfs -t ext4 /dev/sdb 
sudo mkdir /mnt/mydisk 
sudo mount /dev/sdb /mnt/mydisk 
touch /mnt/mydisk/shared_file echo "This is some shared content" | sudo tee /mnt/mydisk/shared_file

on test2 
sudo mkdir /mnt/mydisk
sudo mount /dev/sdb /mnt/mydisk
ls /mnt/mydisk/
cat /mnt/mydisk/shared_file

i can see the shared_file now when i add new files on test1 im not able to see it on test2 untill i unmount the volume with directory and mount the directory again to the volume on test2.

what could be the solution for it? how can i make the volume share datas instantly between all the instances connected to the volume

i have tried with ext4 and xfs file system

Hope to hear from you soon
Thank you!