Where is the bottleneck ?

eva2000

@yokowasis said: But admin can upload 100 images at one batch, or no images at all.

might help for such https://kinsta.com/knowledgebase/bulk-upload-files-wordpress-media-library-ftp/

or via wp-cli https://developer.wordpress.org/cli/commands/media/import/

yokowasis

@jsg said:
We can't really help you/provide good concrete advice with the very limited info piecemeal you provide. So, if you want to get good and useful advice for your situation you must tell us much more.

Thanks. I think I got the help I needed. The database is fine probably. I think the process of writing the image into the disk that hog the IO.

Even a normal cp / backup can bring the websites down.

HDD

root@Ubuntu-1804-bionic-64-minimal /data # dd if=/dev/zero of=test2.img bs=512 count=1000 oflag=dsync
1000+0 records in
1000+0 records out
512000 bytes (512 kB, 500 KiB) copied, 40.0472 s, 12.8 kB/s
root@Ubuntu-1804-bionic-64-minimal /data #

RAID-0 NVME

root@Ubuntu-1804-bionic-64-minimal /mnt/md3 # dd if=/dev/zero of=test2.img bs=512 count=1000 oflag=dsync
1000+0 records in
1000+0 records out
512000 bytes (512 kB, 500 KiB) copied, 1.29931 s, 394 kB/s
root@Ubuntu-1804-bionic-64-minimal /mnt/md3 #

notarobo

why not NVME RAID10.

yokowasis

@notarobo said:
why not NVME RAID10.

too many disk