Proxmox 3.2 - Ceph: Cache Question

[Oer2001]

Hi,

I need some help for the decision what caching option is the best for us.
Very important is, that data loose is not possible.

After read https://pve.proxmox.com/wiki/Performance_Tweaks
the most secure way is to use cache=writethrough. Isn't it?

Our setup is:

LSI 9211-i8 in IT mode (no Cache)
Samsung 840 Pro for OSD's formatted with XFS and mounted with rw,noatime,attr2,discard,inode64,logbufs=8,logbsize=256k,noquota
VM Harddisk Type: SCSI (VIRTIO) with discard option

At the moment we use cache=writeback. But is it safe??

Thank you for help.

Regards

 

[spirit]

At the moment we use cache=writeback. But is it safe??
s

It's safe in term of "you can't break your filesystem", because fsync send by your filesytem is flushing the write buffer correctly.

But you can loose last X seconds of write.