From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx1.redhat.com (ext-mx20.extmail.prod.ext.phx2.redhat.com [10.5.110.49]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 4A4AE5D706 for ; Mon, 13 May 2019 17:25:03 +0000 (UTC) Received: from mr012msb.fastweb.it (mr012msb.fastweb.it [85.18.95.109]) (using TLSv1 with cipher ECDHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 9189C306E171 for ; Mon, 13 May 2019 17:25:00 +0000 (UTC) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Date: Mon, 13 May 2019 19:24:50 +0200 From: Gionatan Danti In-Reply-To: <7e07a7b4-c4c3-bb43-6305-3949c1d1a849@redhat.com> References: <1117624956.13982625.1557612463407.JavaMail.zimbra@karlsbakk.net> <7e07a7b4-c4c3-bb43-6305-3949c1d1a849@redhat.com> Message-ID: <5343bab31e1d4ec5162cd73342388596@assyoma.it> Subject: Re: [linux-lvm] =?utf-8?q?LVM_and_HSM=3F?= 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="us-ascii"; format="flowed" To: LVM general discussion and development Cc: Roy Sigurd Karlsbakk Il 13-05-2019 10:26 Zdenek Kabelac ha scritto: > Hi > > There is no technical problem to enable caching of cached volume (aka > convert cache_cdata LV into another 'cached' volume. > And as long as there are not errors anywhere - it works. > Difficulty comes with solving error cases - and that's the main reason > it's not enable so far. > So I don't see big issue with enabling usage on 'user's own risk'. Hi, how "cache of cached volume" is tiered/hierarchical storage? In such a case, total available space is the sum of all storage hierarchy. For example, using 1 TB SSD + 8 TB HDD would result in 9 TB total in a tiered/hierarchical case, while "only" 8 TB on a cached setup. Am I missing something here? The interesting thing is that LVM already supports something similar to tiered storage, as pvmove can be used to migrate hot physical extent to faster devices. The hard/manual thing is to determine *which* extent to move/migrate. Regards. -- Danti Gionatan Supporto Tecnico Assyoma S.r.l. - www.assyoma.it email: g.danti@assyoma.it - info@assyoma.it GPG public key ID: FF5F32A8