From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mimecast-mx02.redhat.com (mimecast01.extmail.prod.ext.rdu2.redhat.com [10.11.55.17]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 063C820B1B46 for ; Wed, 9 Sep 2020 18:16:38 +0000 (UTC) Received: from us-smtp-1.mimecast.com (us-smtp-delivery-1.mimecast.com [205.139.110.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-SHA384 (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id C23418A19A0 for ; Wed, 9 Sep 2020 18:16:38 +0000 (UTC) MIME-Version: 1.0 Date: Wed, 09 Sep 2020 20:16:26 +0200 From: Gionatan Danti In-Reply-To: <83152674.4938205.1599663690759.JavaMail.zimbra@karlsbakk.net> References: <79061390.1069833.1599071934227.JavaMail.zimbra@karlsbakk.net> <53661d4eefb635710b51cf9bfee894ef@assyoma.it> <83152674.4938205.1599663690759.JavaMail.zimbra@karlsbakk.net> Message-ID: <3503b4f5b55345beb24de4b156ee75c7@assyoma.it> Content-Transfer-Encoding: quoted-printable Subject: Re: [linux-lvm] Looking ahead - tiering with LVM? Reply-To: LVM general discussion and development List-Id: LVM general discussion and development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , List-Id: Content-Type: text/plain; charset="windows-1252"; format="flowed" To: LVM general discussion and development Cc: Roy Sigurd Karlsbakk , =?UTF-8?Q?H=C3=A5kon?= Il 2020-09-09 17:01 Roy Sigurd Karlsbakk ha scritto: > First, filelevel is usually useless. Say you have 50 VMs with Windows > server something. A lot of them are bound to have a ton of equal > storage in the same areas, but the file size and content will vary > over time. With blocklevel tiering, that could work better. It really depends on the use case. I applied it to a fileserver, so=20 working at file level was the right choice. For VMs (or big files) it is=20 useless, I agree. > This is all known. But the only reason to want tiering vs cache is the additional space the=20 former provides. If this additional space is so small (compared to the=20 combined, total volume space), tiering's advantage shrinks to (almost)=20 nothing. > If you look at IOPS instead of just sequencial speed, you'll see the > difference. A set of 10 drives in a RAID-6 will perhaps, maybe, give > you 1kIOPS, while a single SSD might give you 50kIOPS or even more. > This makes a huge impact. IOPs are already well server by LVM cache. So, I genuinely ask: what=20 would be tiering advantage here? I'll love to ear a reasonable use case. > =E2=80=A6which was the reason I asked this question, and which should be = quite > clear in the original post. Yeah, but this need a direct reply from a core LVM developer, which I=20 wellcome ;) Thanks. --=20 Danti Gionatan Supporto Tecnico Assyoma S.r.l. - www.assyoma.it email: g.danti@assyoma.it - info@assyoma.it GPG public key ID: FF5F32A8