<html xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40"><head><meta http-equiv=Content-Type content="text/html; charset=utf-8"><meta name=Generator content="Microsoft Word 15 (filtered medium)"><style></style></head><body lang=EN-US link=blue vlink="#954F72"><div class=WordSection1>Hi Zdenek,Thank you for your email.<o:p> </o:p><ul style='margin-top:0in' type=disc><li class=MsoListParagraph style='margin-left:0in;mso-list:l0 level1 lfo1'>If you know you are going to destroy whole VG - you can simply make sure,<o:p></o:p></li><li class=MsoListParagraph style='margin-left:0in;mso-list:l0 level1 lfo1'>there is no running LV - and just recreate PV/VG from scratch - certainly<o:p></o:p></li><li class=MsoListParagraph style='margin-left:0in;mso-list:l0 level1 lfo1'>faster them removing i.e. thousand of LVs individually one-by-one which<o:p></o:p></li><li class=MsoListParagraph style='margin-left:0in;mso-list:l0 level1 lfo1'>is what will happen with lvremove/vgremove command ATM.<o:p></o:p></li></ul><o:p> </o:p>I tried to follow you for accelerated removal… did I interpret you correctly? I though hit the cache sync stuck issue. Please clarify what needs to change below. I see still cache flush happens while removing the vg.<o:p> </o:p>myhome$ sudo vgcreate pxtest /dev/sdc /dev/nvme0n1 Volume group "pxtest" successfully createdmyhome$myhome$ sudo lvcreate -n cache --type cache-pool -l 100%pvs pxtest /dev/nvme0n1 Logical volume "cache" created.myhome$ sudo lvcreate -n pool --type cache --cachepool pxtest/cache -l 100%pvs pxtest /dev/sdc Logical volume "pool" created.Myhome$<o:p> </o:p>myhome$ sudo lvs pxtest LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert pool pxtest Cwi---C--- 10.00g [cache] [pool_corig]myhome$<o:p> </o:p>myhome$ sudo vgchange -an pxtest 0 logical volume(s) in volume group "pxtest" now activemyhome$ sudo vgremove -ff pxtest 4096 blocks must still be flushed. 4096 blocks must still be flushed. 4096 blocks must still be flushed. 4096 blocks must still be flushed.^CMyhome$<o:p> </o:p>myhome$ sudo dmsetup status pxtest-pool0 20963328 cache 8 40/2048 2048 4096/10220 28 58 0 0 0 0 4096 1 writethrough 2 migration_threshold 2048 cleaner 0 rw -myhome$<o:p> </o:p>myhome$ uname -r4.4.0-131-genericmyhome$ sudo lvm version LVM version: 2.02.133(2) (2015-10-30) Library version: 1.02.110 (2015-10-30) Driver version: 4.34.0myhome$<o:p> </o:p>RegardsLNSent from <a href="https://go.microsoft.com/fwlink/?LinkId=550986">Mail</a> for Windows 10<o:p> </o:p><div style='mso-element:para-border-div;border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0in 0in 0in'>From: <a href="mailto:zkabelac@redhat.com">Zdenek Kabelac</a> Sent: Friday, August 2, 2019 6:14 PM To: <a href="mailto:lvm-devel@redhat.com">LVM2 development</a>; <a href="mailto:lns@portworx.com">Lakshmi Narasimhan Sundararajan</a> Subject: Re: [lvm-devel] lvmcache lv destroy with no flush</div><o:p> </o:p>Dne 01. 08. 19 v 6:50 Lakshmi Narasimhan Sundararajan napsal(a):> Hi Team,> > A very good day to you all.> > Lets say, there exists a LVM cache LV in writeback mode with lots of dirty blocks.> > How can I destroy this LV without waiting for data sync to finish? This is a > tear down operation and there is no necessity for data sync to complete.> > Any operation like lvremove, vgremove etc. all of it wait for the cache sync > to complete before tearing down the lv/vg.> > Please let me know if there is a way to accomplish my requirement.<o:p> </o:p><o:p> </o:p>Currently this is not supported on lvm2 side - we usually want to flush cache first - since we try to keep logic that lvm2 should be reversible for 1-step back.<o:p> </o:p>So we tend to keep things flushed first.<o:p> </o:p>On the other hand - we do have some 'long wanted' feature - like some smart and fast 'accelerated' removal.<o:p> </o:p>i.e. when removing all thin + thin-pool - skip removing individual thins,and similar would apply to cache.<o:p> </o:p>These operation would be irreversible - but certainly much faster.....<o:p> </o:p>On the other hand there is usually way quicker workaround -<o:p> </o:p>If you know you are going to destroy whole VG - you can simply make sure,there is no running LV - and just recreate PV/VG from scratch - certainlyfaster them removing i.e. thousand of LVs individually one-by-one whichis what will happen with lvremove/vgremove command ATM.<o:p> </o:p><o:p> </o:p>2nd. though - when the cache-pool is broken/missing - you can always remove any LV with 'lvremove -ff'<o:p> </o:p>Regards<o:p> </o:p>Zdenek<o:p> </o:p></div></body></html>