Did you thought about RAID 50 ? Messaggio originale Da: matorola@xxxxxxxxx Inviato: 7 dicembre 2019 17:17 A: linux-lvm@xxxxxxxxxx Rispondi a: linux-lvm@xxxxxxxxxx Oggetto: Re: Best way to run LVM over multiple SW RAIDs? On Tue, Oct 29, 2019 at 12:14 PM Daniel Janzon <daniel.janzon@xxxxxxxxxxx> wrote: > > Hello, > > I have a server with very high load using four NVMe SSDs and therefore no HW RAID. Instead I used SW RAID with the mdadm tool. Using one RAID5 volume does not work well since the driver can only utilize one CPU core which spikes at 100% and harms performance. Therefore I created 8 partitions on each disk, and 8 RAID5s across the four disks. > > Now I want to bring them together with LVM. If I do not use a striped volume I get high performance (in expected magnitude according to disk specs). But when I use a striped volume, performance drops to a magnitude below. The reason I am looking for a striped setup is to ensure that data is spread well over the drive to guarantee a good worst-case performance. With linear allocation rather than striped, if load is directed to files on the first PV (a SW RAID) the system is again exposed to the 1-core limitation. > > I tried "--stripes 8 --stripesize 512", and would appreciate any ideas of other things to try. I guess the performance hit can be in the file system as well. I tried XFS and EXT4 with default settings. Daniel, a bit more about your system? Like kernel version, io scheduler, etc.. Have you tried with recent kernels MQ (multi-queue) schedulers (noop, deadline) ? _______________________________________________ linux-lvm mailing list linux-lvm@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/ _______________________________________________ linux-lvm mailing list linux-lvm@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
