Best practice for iSCSI storage domains
What is the best practice for iSCSI storage domains: Many small targets vs a few large targets? Specific example: if you wanted a 8TB storage domain would you prepare a single 8TB LUN or (for example) 8 x 1 TB LUNs. -- Richard Chan
On Thu, Dec 7, 2017 at 9:10 AM, Richard Chan <richard@treeboxsolutions.com> wrote:
What is the best practice for iSCSI storage domains:
Many small targets vs a few large targets?
Specific example: if you wanted a 8TB storage domain would you prepare a single 8TB LUN or (for example) 8 x 1 TB LUNs.
There could be many reasons to use each type.
From the top of my head I think that configuration wise it will be better to configure more than one lun. That can be helpful if you plan to use external LUN disks for example.
Multiple targets might also come useful if you plan to configure iSCSI multipath in the future, that way you can choose only part of the targets to apply the MPIO on.
-- Richard Chan
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This is a multi-part message in MIME format. --------------A77B4AF119B1B92B6F11EC19 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit That's one of the reasons I prefer File storage (like NFS) than iSCSI or Fiberchannel. A lot more flexible and manageable. In the past for VMFS5 I used to work with 4TB LUNs. Now a days something between 4TB and 8TB may be ok given the bigger size of VMs, depending on your enviroment of course. However one thing to take attention in this scenario is how the metadata update process and how that can impact performance on bigger LUNs. Fernando On 07/12/2017 08:51, Maor Lipchuk wrote:
On Thu, Dec 7, 2017 at 9:10 AM, Richard Chan <richard@treeboxsolutions.com <mailto:richard@treeboxsolutions.com>> wrote:
What is the best practice for iSCSI storage domains:
Many small targets vs a few large targets?
Specific example: if you wanted a 8TB storage domain would you prepare a single 8TB LUN or (for example) 8 x 1 TB LUNs.
There could be many reasons to use each type. From the top of my head I think that configuration wise it will be better to configure more than one lun. That can be helpful if you plan to use external LUN disks for example.
Multiple targets might also come useful if you plan to configure iSCSI multipath in the future, that way you can choose only part of the targets to apply the MPIO on.
-- Richard Chan
_______________________________________________ Users mailing list Users@ovirt.org <mailto:Users@ovirt.org> http://lists.ovirt.org/mailman/listinfo/users <http://lists.ovirt.org/mailman/listinfo/users>
_______________________________________________ Users mailing list Users@ovirt.org http://lists.ovirt.org/mailman/listinfo/users
--------------A77B4AF119B1B92B6F11EC19 Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: 8bit <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> </head> <body bgcolor="#FFFFFF" text="#000000"> <p>That's one of the reasons I prefer File storage (like NFS) than iSCSI or Fiberchannel. A lot more flexible and manageable.</p> <p>In the past for VMFS5 I used to work with 4TB LUNs. Now a days something between 4TB and 8TB may be ok given the bigger size of VMs, depending on your enviroment of course. However one thing to take attention in this scenario is how the metadata update process and how that can impact performance on bigger LUNs.</p> <p>Fernando<br> </p> <br> <div class="moz-cite-prefix">On 07/12/2017 08:51, Maor Lipchuk wrote:<br> </div> <blockquote type="cite" cite="mid:CAJ1JNOeoPC0nOsHY3Tsym7nLCr5-o7fQUKsChUWGYDiEeMZf7w@mail.gmail.com"> <div dir="ltr"> <div class="gmail_extra"> <div class="gmail_quote">On Thu, Dec 7, 2017 at 9:10 AM, Richard Chan <span dir="ltr"><<a href="mailto:richard@treeboxsolutions.com" target="_blank" moz-do-not-send="true">richard@treeboxsolutions.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 dir="ltr"> <div> <div>What is the best practice for iSCSI storage domains:<br> <br> </div> Many small targets vs a few large targets?</div> <div><br> </div> <div>Specific example: if you wanted a 8TB storage domain would you prepare a single 8TB LUN or (for example) 8 x 1 TB LUNs.</div> </div> </blockquote> <div><br> </div> <div>There could be many reasons to use each type.</div> <div>From the top of my head I think that configuration wise it will be better to configure more than one lun.</div> <div>That can be helpful if you plan to use external LUN disks for example. <div><br> </div> </div> <div>Multiple targets might also come useful if you plan to configure iSCSI multipath in the future, that way you can choose only part of the targets to apply the MPIO on.</div> <div> </div> <blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"> <div dir="ltr"> <div><span class="gmail-HOEnZb"><font color="#888888"><br> </font></span></div> <span class="gmail-HOEnZb"><font color="#888888"> <div> <div> <div> <div> <div><br> </div> <div><br clear="all"> <br> -- <br> <div class="gmail-m_-4508890179059665979gmail_signature"> <div dir="ltr"> <div> <div dir="ltr"> <div dir="ltr"><font color="#000000" face="Droid Sans"><span style="font-size:15px">Richard Chan</span></font></div> <br> </div> </div> </div> </div> </div> </div> </div> </div> </div> </font></span></div> <br> ______________________________<wbr>_________________<br> Users mailing list<br> <a href="mailto:Users@ovirt.org" moz-do-not-send="true">Users@ovirt.org</a><br> <a href="http://lists.ovirt.org/mailman/listinfo/users" rel="noreferrer" target="_blank" moz-do-not-send="true">http://lists.ovirt.org/<wbr>mailman/listinfo/users</a><br> <br> </blockquote> </div> <br> <br> </div> </div> <br> <fieldset class="mimeAttachmentHeader"></fieldset> <br> <pre wrap="">_______________________________________________ Users mailing list <a class="moz-txt-link-abbreviated" href="mailto:Users@ovirt.org">Users@ovirt.org</a> <a class="moz-txt-link-freetext" href="http://lists.ovirt.org/mailman/listinfo/users">http://lists.ovirt.org/mailman/listinfo/users</a> </pre> </blockquote> <br> </body> </html> --------------A77B4AF119B1B92B6F11EC19--
On Thu, Dec 7, 2017 at 12:51 PM, Maor Lipchuk <mlipchuk@redhat.com> wrote:
On Thu, Dec 7, 2017 at 9:10 AM, Richard Chan <richard@treeboxsolutions.com
wrote:
What is the best practice for iSCSI storage domains:
Many small targets vs a few large targets?
Specific example: if you wanted a 8TB storage domain would you prepare a single 8TB LUN or (for example) 8 x 1 TB LUNs.
There could be many reasons to use each type. From the top of my head I think that configuration wise it will be better to configure more than one lun. That can be helpful if you plan to use external LUN disks for example.
Multiple targets might also come useful if you plan to configure iSCSI multipath in the future, that way you can choose only part of the targets to apply the MPIO on.
That only makes configuration more complex. I think for 8TB, a single LUN should suffice. Y.
-- Richard Chan
_______________________________________________ Users mailing list Users@ovirt.org http://lists.ovirt.org/mailman/listinfo/users
_______________________________________________ Users mailing list Users@ovirt.org http://lists.ovirt.org/mailman/listinfo/users
On 12/07/2017 01:10 AM, Richard Chan wrote:
What is the best practice for iSCSI storage domains:
Many small targets vs a few large targets?
Specific example: if you wanted a 8TB storage domain would you prepare a single 8TB LUN or (for example) 8 x 1 TB LUNs.
There's no "best" answer for this. However, if you know you're going to be doing a ton of VMs (storage), then less is best. The problem with "less" is that you might end up wasting more space for longer periods of time. Not necessarily an issue for subsystems with thin provisioning, but just something to be aware of. The number of virtual disks can get extreme. And while that's not really related to the iSCSI, just getting all those virtual disks online (for example, after node maintenance) can get time consuming. Took me over 30 minutes the other day. Obviously that tends to get worse as the number of virtual disks increases. So, there is something to be said about trying to reduce the number of virtual disks. Our standard for new storage domains is 6TB.
participants (5)
-
Christopher Cox -
FERNANDO FREDIANI -
Maor Lipchuk -
Richard Chan -
Yaniv Kaul