From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id D8376C7EE23 for ; Wed, 1 Mar 2023 23:02:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1677711756; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:in-reply-to:in-reply-to: references:references:list-id:list-help:list-unsubscribe: list-subscribe:list-post; bh=IcdaYkdVklfLfRBkNJX9/ndEkA+srtPgPtEW9vmognc=; b=F/oz3XaEc45/KElGjAfGYf/4iULTnBAjULItu3GSrnpIZ929uph7oiFHaoXxZ1SGb2L95h rdLFcplOckK719ylveaHjUUSfvV8Vr1JNArUAFjxeO47sCEFqUR4OeURmjPQwgUbQKnz/z C705UjHV+99K7Gm/Z51Y0Cj4m7c5TS4= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-582-YDAXCWJxOdWDAV1l8Gx9Ig-1; Wed, 01 Mar 2023 18:02:35 -0500 X-MC-Unique: YDAXCWJxOdWDAV1l8Gx9Ig-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.rdu2.redhat.com [10.11.54.7]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id D91EF811E9C; Wed, 1 Mar 2023 23:02:32 +0000 (UTC) Received: from mm-prod-listman-01.mail-001.prod.us-east-1.aws.redhat.com (unknown [10.30.29.100]) by smtp.corp.redhat.com (Postfix) with ESMTP id 7BC5D140EBF4; Wed, 1 Mar 2023 23:02:31 +0000 (UTC) Received: from mm-prod-listman-01.mail-001.prod.us-east-1.aws.redhat.com (localhost [IPv6:::1]) by mm-prod-listman-01.mail-001.prod.us-east-1.aws.redhat.com (Postfix) with ESMTP id 4805719452CE; Wed, 1 Mar 2023 23:02:31 +0000 (UTC) Received: from smtp.corp.redhat.com (int-mx10.intmail.prod.int.rdu2.redhat.com [10.11.54.10]) by mm-prod-listman-01.mail-001.prod.us-east-1.aws.redhat.com (Postfix) with ESMTP id 0651C19472FC for ; Wed, 1 Mar 2023 23:02:16 +0000 (UTC) Received: by smtp.corp.redhat.com (Postfix) id 13955492B00; Wed, 1 Mar 2023 23:02:16 +0000 (UTC) Received: from mimecast-mx02.redhat.com (mimecast06.extmail.prod.ext.rdu2.redhat.com [10.11.55.22]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 0C9FD492C3E for ; Wed, 1 Mar 2023 23:02:16 +0000 (UTC) Received: from us-smtp-1.mimecast.com (us-smtp-2.mimecast.com [207.211.31.81]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id E50191991C42 for ; Wed, 1 Mar 2023 23:02:15 +0000 (UTC) Received: from out5-smtp.messagingengine.com (out5-smtp.messagingengine.com [66.111.4.29]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_128_GCM_SHA256) id us-mta-281-hAsnf7wyNgqQatcoc6x3Tw-1; Wed, 01 Mar 2023 18:02:14 -0500 X-MC-Unique: hAsnf7wyNgqQatcoc6x3Tw-1 Received: from compute6.internal (compute6.nyi.internal [10.202.2.47]) by mailout.nyi.internal (Postfix) with ESMTP id 169E25C00EC; Wed, 1 Mar 2023 17:55:46 -0500 (EST) Received: from mailfrontend2 ([10.202.2.163]) by compute6.internal (MEProxy); Wed, 01 Mar 2023 17:55:46 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= invisiblethingslab.com; h=cc:cc:content-type:date:date:from:from :in-reply-to:in-reply-to:message-id:mime-version:references :reply-to:sender:subject:subject:to:to; s=fm1; t=1677711346; x= 1677797746; bh=B7cc+QegDbyklNTbsF7aEcHNDjyZLhRsw8RbiXJ65O4=; b=E GApluzRSxCNoAnl8NvxBBEUqFkgbZrvIA5D5KomikoREhTLE+UNl82IK/jVOoy49 QX3Z30Wg0r47LMxPlEi/qZdrQ3EMMe8C3zUX4JTJ5z0Y2LK/YDJmaC7F6AC/pmWM tLbqK5d7CHYDV+YOZgwKQUzbypSnVQWf6h4JOC0ttiwpKYGh9yyMXd983zth1EBp H9OvWGKcnaCnfhsnE5fuxe/DpFONYD0mz0JsaLMBe1MOPuduBtII3538RHD0gl1N Y0zbFMvMCbH7xD8omSDR6RSOCGTS+leoAdA9TieVvZUqezBEgxrqia4NChYugqPo dapAMvUWwVDCiln2g2AYQ== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:cc:content-type:date:date:feedback-id :feedback-id:from:from:in-reply-to:in-reply-to:message-id :mime-version:references:reply-to:sender:subject:subject:to:to :x-me-proxy:x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s= fm1; t=1677711346; x=1677797746; bh=B7cc+QegDbyklNTbsF7aEcHNDjyZ LhRsw8RbiXJ65O4=; b=pJdNsoDJMc9jJEtrNn/oUkguuLWAlO3ex6J4bHGQ9BKf +Z7VuDnyH6IthuRVTePN3hG2FM0AZC8wCfVJvgEhrgwXrCCkpYqWfRDU6cP9pvxB ukfDOZQaFxligFI/Di7pUNNUNw+WCF0G1fKcrVgt4fbf+9iJfH6vNxqR8ayRhpVZ jWJL3ty7crB37W41gFqq3iIr23xhzmod9cHShfAu3wculr7ubwvLkJ92r0ivMybM Kk/JBxVmlU49OkPjuJz6kg/40DbJA28lOilwPKIM189HcMWCaU5YwXowrfmenMZe sM55a9+JfbP6Bbakha8Mj32dmLSdPoiTsCN9gLQ4vA== X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedvhedrudeliedgtdegucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmne cujfgurhepfffhvfevuffkfhggtggujgesghdtreertddtjeenucfhrhhomhepffgvmhhi ucforghrihgvucfqsggvnhhouhhruceouggvmhhisehinhhvihhsihgslhgvthhhihhngh hslhgrsgdrtghomheqnecuggftrfgrthhtvghrnhepvdejteegkefhteduhffgteffgeff gfduvdfghfffieefieekkedtheegteehffelnecuvehluhhsthgvrhfuihiivgeptdenuc frrghrrghmpehmrghilhhfrhhomhepuggvmhhisehinhhvihhsihgslhgvthhhihhnghhs lhgrsgdrtghomh X-ME-Proxy: Feedback-ID: iac594737:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Wed, 1 Mar 2023 17:55:45 -0500 (EST) Date: Wed, 1 Mar 2023 17:55:31 -0500 From: Demi Marie Obenour To: LVM general discussion and development Message-ID: References: <2023967259.761825.1677710640334.JavaMail.zimbra@karlsbakk.net> MIME-Version: 1.0 In-Reply-To: <2023967259.761825.1677710640334.JavaMail.zimbra@karlsbakk.net> X-Scanned-By: MIMEDefang 3.1 on 10.11.54.10 Subject: Re: [linux-lvm] lvconvert --uncache takes hours X-BeenThere: linux-lvm@redhat.com X-Mailman-Version: 2.1.29 Precedence: list List-Id: LVM general discussion and development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: LVM general discussion and development Cc: Malin Bruland Content-Type: multipart/mixed; boundary="===============9035594234405816238==" Errors-To: linux-lvm-bounces@redhat.com Sender: "linux-lvm" X-Scanned-By: MIMEDefang 3.1 on 10.11.54.7 --===============9035594234405816238== Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="Xazqx1JtCBGSCjdU" Content-Disposition: inline --Xazqx1JtCBGSCjdU Content-Type: text/plain; protected-headers=v1; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Date: Wed, 1 Mar 2023 17:55:31 -0500 From: Demi Marie Obenour To: LVM general discussion and development Cc: Malin Bruland Subject: Re: [linux-lvm] lvconvert --uncache takes hours On Wed, Mar 01, 2023 at 11:44:00PM +0100, Roy Sigurd Karlsbakk wrote: > Hi all >=20 > Working with a friend's machine, it has lvmcache turned on with writeback= =2E This has worked well, but now it's uncaching and it takes *hours*. The = amount of cache was chosen to 100GB on an SSD not used for much else and th= e dataset that is being cached, is a RAID-6 set of 10x2TB with XFS on top. = The system mainly works with file serving, but also has some VMs that benef= it from the caching quite a bit. But then - I wonder - how can it spend hou= rs emptying the cache like this? Most write caching I know of last only sec= onds or perhaps in really worst case scenarios, minutes. Since this is taki= ng hours, it looks to me something should have been flushed ages ago. >=20 > Have I (or we) done something very stupid here or is this really how it's= supposed to work? It=E2=80=99s likely normal. HDDs stink at small random writes and RAID-6 m= akes this even worse. That said, I *strongly* recommend using three-disk RAID-1 for the cache, to match the redundancy of the RAID-6. With write-back caching, a failed cache will result in a corrupt and unrecoverable filesystem. --=20 Sincerely, Demi Marie Obenour (she/her/hers) Invisible Things Lab --Xazqx1JtCBGSCjdU Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCgAdFiEEdodNnxM2uiJZBxxxsoi1X/+cIsEFAmP/1+4ACgkQsoi1X/+c IsFMQxAAjrs+xX0ku72g+AyX3cVWbVDsi2y00SkKhUUhZaZi2a+JcPvQadUCCxn4 UTb888HuhY+P6h+BP8m05sgag7BUozjuaaxbETi0MwiI9ZvyuFuXCE56GRaToVqT jSUsrQWLUwRKMtkKXjJ8RVgwsD97xVA6K3erpB2MgAgfLy4o2A+iPP+WhxXyxTOW Udp2gfwuK85lAlnpe9K4yT5Va4MlvBlfAEPO6LCAof6yG7l+YdiDlbWLCVAChEgy jyewsJnfbeXb4S8v/XhULR9XSyZGAopR7x2aer1pL5FJY/N23jYU98cFAAZh7NJc tIp5JTwrV0zRWJlpodlH/XqxELXSAS0B2HqBM7e+ndNxDFbVIdzE+1DLaMRWGA9Q A3XaRa7wYGLpXkLg/PWmc7UahidkMOFGS8vPn1VzDziqoWRWUaUKzlTAW/6Lg9PW CnuccsHYbs0l19+OacmO2nQB+v/qpG7lH9mtPxBDsOB9kg36QHDP4wIEje0GU/44 53XVPp1mZ2XERNdKMSZGrTCKUVoug2XWF+bqFFF6lt2p0V6xzHa6YnFpWRWyVDv0 toV300s7ymnzxt/YuZLYFO5t/9pe25UfZqeQLj26y3jonqEZOhhBzEPyS6pLKaUs eoRlIMcYAlPseEzjg7u6U6c66FhqbzZusjXHVi4TkCcyW62siZ4= =OuhO -----END PGP SIGNATURE----- --Xazqx1JtCBGSCjdU-- --===============9035594234405816238== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ linux-lvm mailing list linux-lvm@redhat.com https://listman.redhat.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/ --===============9035594234405816238==--