TIL AWS doesn't initialize any blocks on your EBS volume until you read from it
1–3 of 3 posts
Re: TIL AWS doesn't initialize any blocks on your EBS volume until you read from it
#2Basically if you never read a particular block from your volume after you initialize it, AWS never moves it out of S3 into EBS.
This can cause bizarrely slow performance for database or other random-read applications when you fire up a volume from a snapshot.
The official mitigation is to literally read every block once and then your volume will perform the way you expect:
sudo fio --filename=/dev/xvdf --rw=randread --bs=128k --iodepth=32 --ioengine=libaio --direct=1 --name=volume-initializeRe: TIL AWS doesn't initialize any blocks on your EBS volume until you read from it
#3Basically if you never read a particular block from your volume after you initialize it, AWS never moves it out of S3 into EBS. This can cause bizarrely slow performance for database or other random-read applications when you fire up a volume from a snapshot. The official mitigation is to literally read every block once and then your volume will perform the way you expect: sudo fio --filename=/dev/xvdf --rw=randread…
That's if you create the volume from a snapshot. You may want to clarify that.
This process can take a long time; sometimes you're better off actually rsyncing the data than using a snapshot.