<div dir="ltr"><div><div><div><div><div><br>Hi Yannis, thank you for your answer. I don't think that the first "partition" is where drbd stores metadata for two reasons:<br></div>1) I'm using internal metadata and, as suggested by the drbd documentation:<br>"Configuring a resource to use internal meta data
means that DRBD stores its meta data on the same physical lower-level
device as the actual production data. It does so by setting aside an
area at the <span class="emphasis"><i>end</i></span> of the device for the specific purpose of storing
metadata."<br></div>2) the /dev/sde1 device appears only after I create an LVM partition on the initiator. This means that there is a really "overlap" between /dev/sde1 and /dev/drbd2 where /dev/sde1 is an LVM partition created on the initiator and /dev/drbd2 is a device created on top of /dev/sde from the drbd cluster.<br><br><br></div>I did another test:<br></div>- I created a partition (type = LINUX, NOT LVM!) on top of /dev/sdd, so I have /dev/sdd1 as a new device<br></div>- I put /dev/drbd2 on top of /dev/sdd1<br><div><div><div><div><div><div>- /dev/drbd2 is used as a backstores in targetcli<br></div><div>- from the initiator I create another partition (LVM)<br><br></div><div>Now it seems all correct from the drbd nodes point of view:<br><br>[root@san2drbdrep ~]# lsblk<br>NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT<br>......<br>sdd 8:48 0 10G 0 disk <br>└─sdd1 8:49 0 10G 0 part <br> └─drbd3 147:3 0 10G 0 disk <br>.....<br>[root@san2drbdrep ~]#<br></div><div><br></div><div>I'm sorry if device names doesn't correspond, but I used a test environment now.<br></div><div>As you can see, now I have /dev/sdd1 on top of /dev/sdd and /dev/drbd3 on top of the partition /dev/sdd1. Furthermore, even though I create an LVM partition on top of /dev/drbd3 (from the initiator), lsblk doesn't show me because I think that lsblk checks only first 2048 sectors on the disk. But this is only a my idea, I need to check. Finally, from the drbd nodes I can see also the LVM partition is I use fdisk:<br><br>[root@san2drbdrep ~]# fdisk /dev/drbd3<br>Welcome to fdisk (util-linux 2.23.2).<br><br>Changes will remain in memory only, until you decide to write them.<br>Be careful before using the write command.<br><br><br>Command (m for help): p<br><br>Disk /dev/drbd3: 10.7 GB, 10736005120 bytes, 20968760 sectors<br>Units = sectors of 1 * 512 = 512 bytes<br>Sector size (logical/physical): 512 bytes / 512 bytes<br>I/O size (minimum/optimal): 512 bytes / 512 bytes<br>Disk label type: dos<br>Disk identifier: 0x482a0701<br><br> Device Boot Start End Blocks Id System<br>/dev/drbd3p1 2048 20968759 10483356 8e Linux LVM<br><br>Command (m for help): q<br><br>[root@san2drbdrep ~]#<br><br><br></div><div>Another interesting question is: Why I don't see vg and lvs on top of /dev/drbd3 from the drbd node with vgscan and lvscan? But This is not a drbd question so I think I have to ask on the LVM mailing list.<br><br></div><div>So, the problem with this solution is that I cannot enlarge the drbd device, but I don't need this. I'm focused on data alignment and performance.<br></div><div><br></div><div>Anyway, I'd like to know if this is the right way to do this. In general it seems to me that using a raw device as drbd backend is not a good idea even though it is possible.<br></div><div><br><br></div><div>Thank you,<br></div><div>Marco<br></div><div><br><br><br><br></div><div><br><br><br><br></div><div><br><br><br><br><div class="gmail_extra"><br><div class="gmail_quote">2017-03-25 14:57 GMT+01:00 Yannis Milios <span dir="ltr"><<a href="mailto:yannis.milios@gmail.com" target="_blank">yannis.milios@gmail.com</a>></span>:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div><div><span style="color:rgb(49,49,49);word-spacing:1px;background-color:rgb(255,255,255)"><br></span></div><div><span style="color:rgb(49,49,49);word-spacing:1px;background-color:rgb(255,255,255)">Not 100% sure but the first 'partition' could be where drbd stores metadata?</span></div><div><span style="color:rgb(49,49,49);word-spacing:1px;background-color:rgb(255,255,255)"><br></span></div><div><span style="color:rgb(49,49,49);word-spacing:1px;background-color:rgb(255,255,255)">Your setup should be fine as long ad you can deal in an easy manner with future resizing of the backing device (sde).</span></div><div><span style="color:rgb(49,49,49);word-spacing:1px;background-color:rgb(255,255,255)"><br></span></div><div><span style="color:rgb(49,49,49);word-spacing:1px;background-color:rgb(255,255,255)">Yannis</span></div><span class="gmail-"><div><span style="color:rgb(49,49,49);word-spacing:1px;background-color:rgb(255,255,255)"><br></span></div><div><span style="color:rgb(49,49,49);word-spacing:1px;background-color:rgb(255,255,255)">root@iscsi2 ~]# lsblk</span><br class="gmail-m_8262290564575384398gmail_msg" style="color:rgb(49,49,49);word-spacing:1px"><span style="color:rgb(49,49,49);word-spacing:1px;background-color:rgb(255,255,255)">NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT</span><br class="gmail-m_8262290564575384398gmail_msg" style="color:rgb(49,49,49);word-spacing:1px"><span style="color:rgb(49,49,49);word-spacing:1px;background-color:rgb(255,255,255)">........</span><br class="gmail-m_8262290564575384398gmail_msg" style="color:rgb(49,49,49);word-spacing:1px"><span style="color:rgb(49,49,49);word-spacing:1px;background-color:rgb(255,255,255)">sde 8:64 0 3,7T 0 disk </span><br class="gmail-m_8262290564575384398gmail_msg" style="color:rgb(49,49,49);word-spacing:1px"><span style="color:rgb(49,49,49);word-spacing:1px;background-color:rgb(255,255,255)">├─sde1 8:65 0 3,7T 0 part </span><br class="gmail-m_8262290564575384398gmail_msg" style="color:rgb(49,49,49);word-spacing:1px"><span style="color:rgb(49,49,49);word-spacing:1px;background-color:rgb(255,255,255)">└─drbd2 147:2 0 3,7T 0 disk </span><br></div></span></div><span class="gmail-HOEnZb"><font color="#888888"><div dir="ltr">-- <br></div><div>Sent from Gmail Mobile</div>
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