Fwd: Multipath iSCSI with several IPs
Hi Dan, The way you describe it I should have 2 storage backends with 2 IPs for the same SAN backend, right? The problem I see is that when you create a disk for a VM, you assign it to only one storage domain... so if the first fails, how will oVirt know which one should use as failover? Thank you 2016-08-04 15:20 GMT+01:00 Dan Yasny <dyasny@gmail.com>:
Normally you 1. enter the IP 2. click discover 3. login to whatever was found 4. enter another IP instead of the first 5. goto 2
On Thu, Aug 4, 2016 at 10:13 AM, James Michels < karma.sometimes.hurts@gmail.com> wrote:
Hello,
I want to add an iSCSI based storage domain. For that I add a domain on the Storage tab with one of the IPs (say 10.10.10.1), but for failover purposes I'd like to use multipath to add a failover IP so if the first one fails, LUNs can be reached via the second (say 10.10.10.2).
How can this be done in oVirt 4.0.1? I have not seen a way how to add the second IP for multipath purposes.
Thank you
James
_______________________________________________ Users mailing list Users@ovirt.org http://lists.ovirt.org/mailman/listinfo/users
This is a multi-part message in MIME format. --------------CF1B13BDC492754DABFED2A7 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit On 04/08/16 15:37, James Michels wrote:
Hi Dan,
The way you describe it I should have 2 storage backends with 2 IPs for the same SAN backend, right? The problem I see is that when you create a disk for a VM, you assign it to only one storage domain... so if the first fails, how will oVirt know which one should use as failover?
No, multipath is the *same* storage (ie LUN) exposed via two different network paths. Alex -- This message is intended only for the addressee and may contain confidential information. Unless you are that person, you may not disclose its contents or use it in any way and are requested to delete the message along with any attachments and notify us immediately. This email is not intended to, nor should it be taken to, constitute advice. The information provided is correct to our knowledge & belief and must not be used as a substitute for obtaining tax, regulatory, investment, legal or any other appropriate advice. "Transact" is operated by Integrated Financial Arrangements Ltd. 29 Clement's Lane, London EC4N 7AE. Tel: (020) 7608 4900 Fax: (020) 7608 5300. (Registered office: as above; Registered in England and Wales under number: 3727592). Authorised and regulated by the Financial Conduct Authority (entered on the Financial Services Register; no. 190856). --------------CF1B13BDC492754DABFED2A7 Content-Type: text/html; charset=windows-1252 Content-Transfer-Encoding: 7bit <html> <head> <meta content="text/html; charset=windows-1252" http-equiv="Content-Type"> </head> <body bgcolor="#FFFFFF" text="#000000"> <p>On 04/08/16 15:37, James Michels wrote:<br> </p> <blockquote cite="mid:CALws9xWUKP9_UBqVYjiyPbNUBn1SBdVwJn7H-SJR-1_FXZ2rFQ@mail.gmail.com" type="cite"> <div dir="ltr"> <div class="gmail_quote"> <div dir="ltr">Hi Dan, <div><br> </div> <div>The way you describe it I should have 2 storage backends with 2 IPs for the same SAN backend, right? The problem I see is that when you create a disk for a VM, you assign it to only one storage domain... so if the first fails, how will oVirt know which one should use as failover?</div> <div><br> </div> <br> </div> </div> </div> </blockquote> No, multipath is the *same* storage (ie LUN) exposed via two different network paths.<br> <br> Alex<br> <br><pre> -- This message is intended only for the addressee and may contain confidential information. Unless you are that person, you may not disclose its contents or use it in any way and are requested to delete the message along with any attachments and notify us immediately. This email is not intended to, nor should it be taken to, constitute advice. The information provided is correct to our knowledge & belief and must not be used as a substitute for obtaining tax, regulatory, investment, legal or any other appropriate advice. "Transact" is operated by Integrated Financial Arrangements Ltd. 29 Clement's Lane, London EC4N 7AE. Tel: (020) 7608 4900 Fax: (020) 7608 5300. (Registered office: as above; Registered in England and Wales under number: 3727592). Authorised and regulated by the Financial Conduct Authority (entered on the Financial Services Register; no. 190856). </pre><br> </body> </html> --------------CF1B13BDC492754DABFED2A7--
On Thu, Aug 4, 2016 at 10:37 AM, James Michels < karma.sometimes.hurts@gmail.com> wrote:
Hi Dan,
The way you describe it I should have 2 storage backends with 2 IPs for the same SAN backend, right?
Every iSCSI SAN has multiple portals (usually one on each storage controller, and each with it's own IP), and when you create a target you assign it the portals through which it should be accessible. So if you have two portals (two IPs) assigned to a target (LUN), you can access it via two paths, each path leading through a different portal/IP to the same target/LUN. What do you use for your iSCSI backend?
The problem I see is that when you create a disk for a VM, you assign it to only one storage domain... so if the first fails, how will oVirt know which one should use as failover?
There is only one disk, but it sits on a target, which can be accessed via two different IPs. oVirt stores all the iSCSI portal IPs you give it as described in my first response in a database, and connects to them when connecting to the storage domain. If one is down, multipath will mark the path as down and keep using other IPs to access the same LUN
Thank you
2016-08-04 15:20 GMT+01:00 Dan Yasny <dyasny@gmail.com>:
Normally you 1. enter the IP 2. click discover 3. login to whatever was found 4. enter another IP instead of the first 5. goto 2
On Thu, Aug 4, 2016 at 10:13 AM, James Michels < karma.sometimes.hurts@gmail.com> wrote:
Hello,
I want to add an iSCSI based storage domain. For that I add a domain on the Storage tab with one of the IPs (say 10.10.10.1), but for failover purposes I'd like to use multipath to add a failover IP so if the first one fails, LUNs can be reached via the second (say 10.10.10.2).
How can this be done in oVirt 4.0.1? I have not seen a way how to add the second IP for multipath purposes.
Thank you
James
_______________________________________________ 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
Nice, now it's crystal clear. This is an Huawei Oceanstor disk array which we want to test with ovirt so we can see performance, how ovirt behaves with situations where one controller is disconnected etc., that's why we wanted to implement multipath. Thanks for the insight! James 2016-08-04 15:42 GMT+01:00 Dan Yasny <dyasny@gmail.com>:
On Thu, Aug 4, 2016 at 10:37 AM, James Michels < karma.sometimes.hurts@gmail.com> wrote:
Hi Dan,
The way you describe it I should have 2 storage backends with 2 IPs for the same SAN backend, right?
Every iSCSI SAN has multiple portals (usually one on each storage controller, and each with it's own IP), and when you create a target you assign it the portals through which it should be accessible. So if you have two portals (two IPs) assigned to a target (LUN), you can access it via two paths, each path leading through a different portal/IP to the same target/LUN. What do you use for your iSCSI backend?
The problem I see is that when you create a disk for a VM, you assign it to only one storage domain... so if the first fails, how will oVirt know which one should use as failover?
There is only one disk, but it sits on a target, which can be accessed via two different IPs. oVirt stores all the iSCSI portal IPs you give it as described in my first response in a database, and connects to them when connecting to the storage domain. If one is down, multipath will mark the path as down and keep using other IPs to access the same LUN
Thank you
2016-08-04 15:20 GMT+01:00 Dan Yasny <dyasny@gmail.com>:
Normally you 1. enter the IP 2. click discover 3. login to whatever was found 4. enter another IP instead of the first 5. goto 2
On Thu, Aug 4, 2016 at 10:13 AM, James Michels < karma.sometimes.hurts@gmail.com> wrote:
Hello,
I want to add an iSCSI based storage domain. For that I add a domain on the Storage tab with one of the IPs (say 10.10.10.1), but for failover purposes I'd like to use multipath to add a failover IP so if the first one fails, LUNs can be reached via the second (say 10.10.10.2).
How can this be done in oVirt 4.0.1? I have not seen a way how to add the second IP for multipath purposes.
Thank you
James
_______________________________________________ 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
participants (3)
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Alex Crow -
Dan Yasny -
James Michels