<div dir="ltr"><div><div>Hi,<br><br></div>The fields "discard" and "postZero" are sent to vdsm by the engine in order to implement the "Discard After Delete" and "Wipe After Delete" features.</div><div><br></div>When a storage domain is marked with Discard After Delete, a disk that is removed from that storage domain is discarded before it's removed. This way, the disk's blocks are freed from the storage array and can be used by other LUNs in the array.<br>For more information about Discard After Delete, please refer to the feature page [1].<br><br><div>When a disk (on a block storage domain) is marked with Wipe After Delete, it is wiped right before it's removed. The idea behind this is that when the disk contains sensitive data, the administrator doesn't want it to be read after it is removed. However, when we don't wipe a disk's blocks before it is removed, the data can be read by a new VM user with a disk that is created on some/all the blocks of the old disk.</div><div>For more information about Wipe After Delete, please refer to the administrator guide [2].</div><div><br></div><div>If you have any further questions, please don't hesitate to ask.<br></div><div><br></div><div>Regards,<br></div><div class="gmail_extra"><div><div class="gmail_signature"><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr">Idan</div><div dir="ltr"><br></div><div>[1] <a href="https://www.ovirt.org/develop/release-management/features/storage/discard-after-delete/">https://www.ovirt.org/develop/release-management/features/storage/discard-after-delete/</a></div><div>[2] <a href="https://www.ovirt.org/documentation/admin-guide/chap-Virtual_Machine_Disks/#settings-to-wipe-virtual-disks-after-deletion">https://www.ovirt.org/documentation/admin-guide/chap-Virtual_Machine_Disks/#settings-to-wipe-virtual-disks-after-deletion</a><br></div></div></div></div></div></div></div>
<br><div class="gmail_quote">On Wed, Jan 3, 2018 at 4:33 AM, pengyixiang <span dir="ltr"><<a href="mailto:yxpengi386@163.com" target="_blank">yxpengi386@163.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div style="line-height:1.7;color:rgb(0,0,0);font-size:14px;font-family:Arial"><div>hello, everyone!</div><div> when Image.delete called in vdsm, we need a param "discart" in [1], then I find is just supported by block and <span style="color:rgb(0,128,0);font-weight:bold;font-family:"DejaVu Sans Mono";font-size:11.3pt;white-space:pre-wrap">"/sbin/blkdiscard" </span>called in last in [2], but </div><div>I don't know why we need to discard the block devices rather than directly use "<span style="color:rgb(0,128,0);font-weight:bold;font-family:"DejaVu Sans Mono";font-size:11.3pt;white-space:pre-wrap">rm -f</span>" ? and what time we need set "<span style="color:rgb(0,128,0);font-weight:bold;font-family:"DejaVu Sans Mono";font-size:11.3pt;white-space:pre-wrap">discart = TRUE" </span>?</div><div> And what time we should set "<span style="color:rgb(0,128,0);font-weight:bold;font-family:"DejaVu Sans Mono";font-size:11.3pt;white-space:pre-wrap">postZero=TRUE</span>" ?</div><div><br></div><div><br></div><div>[1] <span style="color:rgb(36,41,46);font-family:SFMono-Regular,Consolas,"Liberation Mono",Menlo,Courier,monospace;font-size:12px;white-space:pre-wrap"><a href="https://github.com/oVirt/vdsm/blob/2b98daffb2c2dec1bbbd3427d3d32861d77f01a7/lib/vdsm/API.py#L841" target="_blank">https://github.com/oVirt/<wbr>vdsm/blob/<wbr>2b98daffb2c2dec1bbbd3427d3d328<wbr>61d77f01a7/lib/vdsm/API.py#<wbr>L841</a></span></div><div><span style="color:rgb(36,41,46);font-family:SFMono-Regular,Consolas,"Liberation Mono",Menlo,Courier,monospace;font-size:12px;white-space:pre-wrap">[2]</span><span style="color:rgb(36,41,46);font-family:SFMono-Regular,Consolas,"Liberation Mono",Menlo,Courier,monospace;font-size:12px;white-space:pre-wrap"><a href="https://github.com/oVirt/vdsm/blob/2b98daffb2c2dec1bbbd3427d3d32861d77f01a7/lib/vdsm/storage/blockSD.py#L714" target="_blank">https://github.com/oVirt/<wbr>vdsm/blob/<wbr>2b98daffb2c2dec1bbbd3427d3d328<wbr>61d77f01a7/lib/vdsm/storage/<wbr>blockSD.py#L714</a></span><span style="color:rgb(36,41,46);font-family:SFMono-Regular,Consolas,"Liberation Mono",Menlo,Courier,monospace;font-size:12px;white-space:pre-wrap"> </span></div></div><br><br><span title="neteasefooter"><p> </p></span><br>______________________________<wbr>_________________<br>
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