Sizing the master storage domain
Hi, I know Itamar explained that the notion of master storage domain will disappear in some releases. But now, with a 3.4 I'm installing, I was wondering : - on my other oVirt setups, I started with one big (iSCSI) LUN, which is the master, and stored as many VMs I could - when space came to miss, I added another LUN, the another... - when I have to do some maintenance (grow, disable, other...) on a LUN, I can move my VM disks amongst the normal storage domains. When Empty, I can switch them off, add others, and so on The only one I can not play with is the master one. I came to think that I had no benefice storing anything on the master storage domain, and use only the normal storage domains. And then, I came to think I had no reason to dedicate a huge LUN for the master. Ok, but according to you, what is the minimum reasonable size for a master storage domain? -- Nicolas Ecarnot
On 09/18/2014 02:27 PM, Nicolas Ecarnot wrote:
Hi,
I know Itamar explained that the notion of master storage domain will disappear in some releases. But now, with a 3.4 I'm installing, I was wondering :
- on my other oVirt setups, I started with one big (iSCSI) LUN, which is the master, and stored as many VMs I could - when space came to miss, I added another LUN, the another... - when I have to do some maintenance (grow, disable, other...) on a LUN, I can move my VM disks amongst the normal storage domains. When Empty, I can switch them off, add others, and so on
The only one I can not play with is the master one. I came to think that I had no benefice storing anything on the master storage domain, and use only the normal storage domains.
And then, I came to think I had no reason to dedicate a huge LUN for the master.
Ok, but according to you, what is the minimum reasonable size for a master storage domain?
you should be able to move master domain to maint (deactivate, not detach) as well (full or empty). engine will just configure another storage domain as master iirc.
Le 18/09/2014 13:30, Itamar Heim a écrit :
On 09/18/2014 02:27 PM, Nicolas Ecarnot wrote:
Hi,
I know Itamar explained that the notion of master storage domain will disappear in some releases. But now, with a 3.4 I'm installing, I was wondering :
- on my other oVirt setups, I started with one big (iSCSI) LUN, which is the master, and stored as many VMs I could - when space came to miss, I added another LUN, the another... - when I have to do some maintenance (grow, disable, other...) on a LUN, I can move my VM disks amongst the normal storage domains. When Empty, I can switch them off, add others, and so on
The only one I can not play with is the master one. I came to think that I had no benefice storing anything on the master storage domain, and use only the normal storage domains.
And then, I came to think I had no reason to dedicate a huge LUN for the master.
Ok, but according to you, what is the minimum reasonable size for a master storage domain?
you should be able to move master domain to maint (deactivate, not detach) as well (full or empty). engine will just configure another storage domain as master iirc.
This is a nice feature, but as detaching (then removing) is needed, my question still remains. -- Nicolas Ecarnot
On 09/18/2014 02:32 PM, Nicolas Ecarnot wrote:
Le 18/09/2014 13:30, Itamar Heim a écrit :
On 09/18/2014 02:27 PM, Nicolas Ecarnot wrote:
Hi,
I know Itamar explained that the notion of master storage domain will disappear in some releases. But now, with a 3.4 I'm installing, I was wondering :
- on my other oVirt setups, I started with one big (iSCSI) LUN, which is the master, and stored as many VMs I could - when space came to miss, I added another LUN, the another... - when I have to do some maintenance (grow, disable, other...) on a LUN, I can move my VM disks amongst the normal storage domains. When Empty, I can switch them off, add others, and so on
The only one I can not play with is the master one. I came to think that I had no benefice storing anything on the master storage domain, and use only the normal storage domains.
And then, I came to think I had no reason to dedicate a huge LUN for the master.
Ok, but according to you, what is the minimum reasonable size for a master storage domain?
you should be able to move master domain to maint (deactivate, not detach) as well (full or empty). engine will just configure another storage domain as master iirc.
This is a nice feature, but as detaching (then removing) is needed, my question still remains.
master storage domains is a normal storage domain. it only happens to be using its "special metadata part" as the master. so all storage domains have it. if its down, engine will automatically select another one. iirc, we need 2GB for meta data (on block storage. NFS is allocated as needed). iirc, we block or warn on creating storage domains of <10GB.
Le 18/09/2014 13:35, Itamar Heim a écrit :
On 09/18/2014 02:32 PM, Nicolas Ecarnot wrote:
Le 18/09/2014 13:30, Itamar Heim a écrit :
On 09/18/2014 02:27 PM, Nicolas Ecarnot wrote:
Hi,
I know Itamar explained that the notion of master storage domain will disappear in some releases. But now, with a 3.4 I'm installing, I was wondering :
- on my other oVirt setups, I started with one big (iSCSI) LUN, which is the master, and stored as many VMs I could - when space came to miss, I added another LUN, the another... - when I have to do some maintenance (grow, disable, other...) on a LUN, I can move my VM disks amongst the normal storage domains. When Empty, I can switch them off, add others, and so on
The only one I can not play with is the master one. I came to think that I had no benefice storing anything on the master storage domain, and use only the normal storage domains.
And then, I came to think I had no reason to dedicate a huge LUN for the master.
Ok, but according to you, what is the minimum reasonable size for a master storage domain?
you should be able to move master domain to maint (deactivate, not detach) as well (full or empty). engine will just configure another storage domain as master iirc.
This is a nice feature, but as detaching (then removing) is needed, my question still remains.
master storage domains is a normal storage domain. it only happens to be using its "special metadata part" as the master. so all storage domains have it. if its down, engine will automatically select another one.
Itamar, and others, Just a little word to explain that I've just finished to test the feature you described above (automatic master storage domain switching) and it is working nicely, and very quickly. This is very cool and useful. Thank you. -- Nicolas Ecarnot
iirc, we need 2GB for meta data (on block storage. NFS is allocated as needed). iirc, we block or warn on creating storage domains of <10GB.
-- Nicolas Ecarnot
Le 27/10/2014 10:32, Nicolas Ecarnot a écrit :
Le 18/09/2014 13:35, Itamar Heim a écrit :
you should be able to move master domain to maint (deactivate, not detach) as well (full or empty). engine will just configure another storage domain as master iirc.
This is a nice feature, but as detaching (then removing) is needed, my question still remains.
master storage domains is a normal storage domain. it only happens to be using its "special metadata part" as the master. so all storage domains have it. if its down, engine will automatically select another one.
Itamar, and others,
Just a little word to explain that I've just finished to test the feature you described above (automatic master storage domain switching) and it is working nicely, and very quickly. This is very cool and useful.
Trying something very similar, but on a production setup, so I don't want to mess everything : Can I put a master storage domain into maintenance mode, when it contains some running VMs? Is yes, what will be the effect? Will it only transfer the master metadata parts to another storage domain, or will it also put it into read-only mode or other actions? Thank you. -- Nicolas Ecarnot
On 11/19/2014 10:50 AM, Nicolas Ecarnot wrote:
Le 27/10/2014 10:32, Nicolas Ecarnot a écrit :
Le 18/09/2014 13:35, Itamar Heim a écrit :
you should be able to move master domain to maint (deactivate, not detach) as well (full or empty). engine will just configure another storage domain as master iirc.
This is a nice feature, but as detaching (then removing) is needed, my question still remains.
master storage domains is a normal storage domain. it only happens to be using its "special metadata part" as the master. so all storage domains have it. if its down, engine will automatically select another one.
Itamar, and others,
Just a little word to explain that I've just finished to test the feature you described above (automatic master storage domain switching) and it is working nicely, and very quickly. This is very cool and useful.
Trying something very similar, but on a production setup, so I don't want to mess everything : Can I put a master storage domain into maintenance mode, when it contains some running VMs? Is yes, what will be the effect? Will it only transfer the master metadata parts to another storage domain, or will it also put it into read-only mode or other actions?
Thank you.
if the running VMs are from that storage domain, it shouldn't allow you to move it to maintenance (I hope)
participants (2)
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Itamar Heim -
Nicolas Ecarnot