From mboxrd@z Thu Jan 1 00:00:00 1970 From: chickenmarkus@freenet.de Subject: Re: Fwd: Discard is not working Date: Fri, 07 Feb 2014 21:19:34 +0100 Message-ID: <52F53FD6.80509@freenet.de> References: <52F2C104.4040503@freenet.de> <52F422C2.9020509@redhat.com> <52F50BA3.10309@msgid.tls.msk.ru> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15; format=flowed Content-Transfer-Encoding: 7bit To: kvm@vger.kernel.org Return-path: Received: from mout0.freenet.de ([195.4.92.90]:59799 "EHLO mout0.freenet.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752842AbaBGUVj (ORCPT ); Fri, 7 Feb 2014 15:21:39 -0500 Received: from [195.4.92.141] (helo=mjail1.freenet.de) by mout0.freenet.de with esmtpa (ID chickenmarkus@freenet.de) (port 25) (Exim 4.80.1 #4) id 1WBrvd-0004Oj-JQ for kvm@vger.kernel.org; Fri, 07 Feb 2014 21:21:37 +0100 Received: from localhost ([::1]:42882 helo=mjail1.freenet.de) by mjail1.freenet.de with esmtpa (ID chickenmarkus@freenet.de) (Exim 4.80.1 #4) id 1WBrvd-0000zi-Fq for kvm@vger.kernel.org; Fri, 07 Feb 2014 21:21:37 +0100 Received: from mx13.freenet.de ([195.4.92.23]:57796) by mjail1.freenet.de with esmtpa (ID chickenmarkus@freenet.de) (Exim 4.80.1 #4) id 1WBrtg-0002V5-GD for kvm@vger.kernel.org; Fri, 07 Feb 2014 21:19:36 +0100 Received: from p54b52823.dip0.t-ipconnect.de ([84.181.40.35]:34536 helo=[192.168.178.35]) by mx13.freenet.de with esmtpsa (ID chickenmarkus@freenet.de) (TLSv1:DHE-RSA-CAMELLIA256-SHA:256) (port 587) (Exim 4.80.1 #4) id 1WBrtg-0003fV-B8 for kvm@vger.kernel.org; Fri, 07 Feb 2014 21:19:36 +0100 In-Reply-To: <52F50BA3.10309@msgid.tls.msk.ru> Sender: kvm-owner@vger.kernel.org List-ID: Hello, I played around with raw images now. Megasas is not supported by libvirt. The default controller crashs during installation while accessing to disk. qemu-system-x86_64: /build/qemu-j0uSxv/qemu-1.7.0+dfsg/hw/scsi/lsi53c895a.c:541: lsi_do_dma: Assertion `s->current' failed. So I took Debian Testing (Jessie with kernel 3.12) to use virtio-scsi over following options. -device virtio-scsi-pci,id=scsi0,bus=pci.0,addr=0x4 \ -drive file=/home/vm/trim.raw,if=none,id=drive-scsi0-0-0-0,format=raw,discard=unmap \ -device scsi-hd,bus=scsi0.0,channel=0,scsi-id=0,lun=0,drive=drive-scsi0-0-0-0,id=scsi0-0-0-0,bootindex=2 Result of this: fstrim works. Take a look into lsblk -D: DISC-ZERO=0? I read DISC-ZERO has to be "1" to propagate discard. Switch back to my thin volume vm. DISC-ZERO=0 and fstrim works! Booting from old kernel 3.2 - works too. LVM recognize the increasing of thin volume after discard. Conclusion of my issues: > Did I understand something wrong? Yes! Discard granularity (DISC-GRAN) of lsblk -D is the important number. It must not be "0B". I did so much the last weeks. Maybe the error of fstrim occurs before getting thin volumes work. Thanks a lot for your help (and hint to try it with an image)! Bye Markus Am 07.02.2014 17:36, schrieb Michael Tokarev: > 07.02.2014 04:03, Paolo Bonzini wrote: >> Michael, can you look at this? >> >> Paolo >> >> -------- Messaggio originale -------- >> From: chickenmarkus@freenet.de >> To: kvm@vger.kernel.org >> >> Hello, >> >> after reading the "invitation" for some one-off questions without >> subscribing excuse my disturbing, please. >> >> At first my setup of host: >> >> * in general Debian Wheezy >> * Kernel: 3.11-0.bpo.2-amd64 >> >> (http://packages.debian.org/wheezy-backports/linux-image-3.11-0.bpo.2-amd64) >> * LVM 2.02.98 (http://packages.debian.org/jessie/lvm2) >> * thin-provisioning-tools 0.2.8-1 >> (http://packages.debian.org/jessie/thin-provisioning-tools) >> * Qemu-KVM: 1.7.0 (http://packages.debian.org/jessie/qemu-kvm) >> >> The new kernel and dirty things from Jessie are for working thin volumes >> with discard on my ssd. Everything's fine up to this point. >> >> Afterwards I start a guest (also Debian Wheezy) over the following >> command (over libvirt) as root (for test only): >> >> kvm [...] -drive >> >> file=/dev/ssd0/sarabi,if=none,id=drive-scsi0-0-0-0,format=raw,discard=unmap -device >> scsi-hd,bus=scsi0.0,channel=0,scsi-id=0,lun=0,drive=drive-scsi0-0-0-0,id=scsi0-0-0-0,bootindex=2 >> [...] >> >> Neither lsblk -D nor the try of fstrim ends positive. Both say that >> discard is not supported. >> I read that guests need at least kernel 3.4 to support discard (and >> virtio-scsi). But the same backports kernel 3.11 did not changed anything. > This is the first time I tried to deal with discard. I've no discard-capable > hardware, so never bothered to even look how it works (or not). > > I fired up my sample linux guest here, using 3.10 kernel on host and 3.2 kernel > on guest, using something similar to what your command looks like: > > -device megasas,id=scsi0 \ > -drive file=test.raw,if=none,id=sd0,discard=unmap \ > -device scsi-hd,bus=scsi0.0,channel=0,scsi-id=0,lun=0,drive=sd0 > > Note: this is a plain file (test.raw) on an ext4 filesystem on a device > without discard support (regular rotational hard drive). > > In the guest, I can see discard granularity (4K) for that drive in lsblk -D > output. > > fstrim does not error out, but I don't know if it actually does something or > not. > > The same result can be observed with 3.10 kernel in guest, and with other > scsi devices/drivers (eg lsi53c895a). > > However, when I export the same test.raw file using virtio, like this: > > -drive file=test.raw,if=virtio,discard=unmap > > it doesn't work: guest does not see the virtio drive as discardable. > >> Did I understand something wrong? Is the command wrong? Are any >> requirements not met? > So I've no idea what's going on here... ;) > > Thanks, > > /mjt > > -- > To unsubscribe from this list: send the line "unsubscribe kvm" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html