On Wed, Aug 16, 2017 at 4:37 PM, FERNANDO FREDIANI < [email protected]> wrote:
> Hello > > I just wanted to share a scenario with you and perhaps exchange more > information with other people that may also have a similar scenario. > > For a couple of months I have been running a oVirt Node (CentOS 7.3 > Minimal) with bcache (https://bcache.evilpiepirate.org/) for caching a > SSD with HDD disks. The setup is simple and was made for a prof of concept > and since them has been working better than expected. > This is a standalone host with 4 disks being: 1 for Operating System, 2 x > 2TB 7200 RPM in software RAID 1 and 1 x PCI-E NVMe 400GB SSD which plays > the caching device for both reads and writes. The VM storage folder is > mounted as a ext4 partition on the logical device created by bcache > (/dev/bcache0). All this is transparent to oVirt as all it sees is a > /folder to put the VMs. > > We monitor the IOPS on all block devices individually and see the behavior > exactly as expected: random writes are all done on the SSD first and them > streamed sequentially to the mechanical drives with pretty impressive > performance. Also in the beginning while the total amount of data was less > than 400GB ALL read used to come from the caching device and therefore > didn't use IOPS from the mechanical drives leaving it free to do basically > writes. Finally at sequential IOPS (as described by bcache) are > intelligently passed directly to the mechanical drives (but they are not > much). > > Although bcache is present on kernel 3.10 I had to use kernel-ml 4.12 > (from Elrepo) and I had also to compile the bcache-tools as I could not > find it available in any repository. > Nice! It'd be great if you could write an ovirt.org blog about setting it up and how it worked for you in. Have you considered using dm-cache? Y. > > Regards > Fernando > > _______________________________________________ > Users mailing list > [email protected] > http://lists.ovirt.org/mailman/listinfo/users > >
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