On 09/04/18 16:49, Vincent Royer wrote:> > > Is a flash-backed Raid required for JBOD, and should it be 1gb, 2, > or 4gb flash? > >RAID and JBOD are completely different things. JBODs are just that, bunches of disks, and they don't have any cache above them in hardware. If you're going to use ZFS under Gluster, look at the ZFS docs first. Short answer is no. If Gluster passes sync writes down to the lower level FS as sync, and you decide to use a ZFS SLOG device, usually an SSD, it should have power fail protection capacitors. Do *not* use a RAID controller for ZFS, use a decent HBA instead, so ZFS can access the disks directly. Using a RAID controller is not only wasteful it's setting yourself up for a world of pain when a ZFS VDEV member device fails. Don't do it. -- This message is intended only for the addressee and may contain confidential information. Unless you are that person, you may not disclose its contents or use it in any way and are requested to delete the message along with any attachments and notify us immediately. This email is not intended to, nor should it be taken to, constitute advice. The information provided is correct to our knowledge & belief and must not be used as a substitute for obtaining tax, regulatory, investment, legal or any other appropriate advice. "Transact" is operated by Integrated Financial Arrangements Ltd. 29 Clement's Lane, London EC4N 7AE. Tel: (020) 7608 4900 Fax: (020) 7608 5300. (Registered office: as above; Registered in England and Wales under number: 3727592). Authorised and regulated by the Financial Conduct Authority (entered on the Financial Services Register; no. 190856). -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.gluster.org/pipermail/gluster-users/attachments/20180409/0e6dad5a/attachment.html>
Thanks, I suppose what I'm trying to gain is some clarity on what choice is best for a given application. How do I know if it's better for me to use a raid card or not, to include flash-cache on it or not, to use ZFS or not, when combined with a small number of SSDs in Replica 3. On Mon, Apr 9, 2018 at 10:49 AM, Alex Crow <acrow at integrafin.co.uk> wrote:> On 09/04/18 16:49, Vincent Royer wrote: > > >> Is a flash-backed Raid required for JBOD, and should it be 1gb, 2, or 4gb >> flash? >> > > RAID and JBOD are completely different things. JBODs are just that, > bunches of disks, and they don't have any cache above them in hardware. If > you're going to use ZFS under Gluster, look at the ZFS docs first. Short > answer is no. If Gluster passes sync writes down to the lower level FS as > sync, and you decide to use a ZFS SLOG device, usually an SSD, it should > have power fail protection capacitors. > > Do *not* use a RAID controller for ZFS, use a decent HBA instead, so ZFS > can access the disks directly. Using a RAID controller is not only wasteful > it's setting yourself up for a world of pain when a ZFS VDEV member device > fails. Don't do it. > > > -- > This message is intended only for the addressee and may contain > confidential information. Unless you are that person, you may not > disclose its contents or use it in any way and are requested to delete > the message along with any attachments and notify us immediately. > This email is not intended to, nor should it be taken to, constitute advice. > The information provided is correct to our knowledge & belief and must not > be used as a substitute for obtaining tax, regulatory, investment, legal or > any other appropriate advice. > > "Transact" is operated by Integrated Financial Arrangements Ltd. > 29 Clement's Lane, London EC4N 7AE. Tel: (020) 7608 4900 Fax: (020) 7608 5300. > (Registered office: as above; Registered in England and Wales under > number: 3727592). Authorised and regulated by the Financial Conduct > Authority (entered on the Financial Services Register; no. 190856). > > > > _______________________________________________ > Gluster-users mailing list > Gluster-users at gluster.org > http://lists.gluster.org/mailman/listinfo/gluster-users >-------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.gluster.org/pipermail/gluster-users/attachments/20180409/0f1c4f12/attachment.html>
On 09/04/18 19:02, Vincent Royer wrote:> Thanks, > > I suppose what I'm trying to gain is some clarity on what choice is > best for a given application.? How do I know if it's better for me to > use a raid card or not, to include flash-cache on it or not, to use > ZFS or not, when combined with a small number of SSDs in Replica 3. > >How few is "small number" - most importantly number per server? Replica 3 is a start, as it already tells us you can lose at one entire server and carry on as normal. If you lose two, your GlusterFS is down. What is your resilience goal? You should really be starting with requirements, not speccing out and buying servers and drives and then trying to force them to fit your expectations. -- This message is intended only for the addressee and may contain confidential information. Unless you are that person, you may not disclose its contents or use it in any way and are requested to delete the message along with any attachments and notify us immediately. This email is not intended to, nor should it be taken to, constitute advice. The information provided is correct to our knowledge & belief and must not be used as a substitute for obtaining tax, regulatory, investment, legal or any other appropriate advice. "Transact" is operated by Integrated Financial Arrangements Ltd. 29 Clement's Lane, London EC4N 7AE. Tel: (020) 7608 4900 Fax: (020) 7608 5300. (Registered office: as above; Registered in England and Wales under number: 3727592). Authorised and regulated by the Financial Conduct Authority (entered on the Financial Services Register; no. 190856). -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.gluster.org/pipermail/gluster-users/attachments/20180409/d31afd42/attachment.html>