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From: "M. Mohan Kumar" <mohan@in.ibm.com>
To: thornber@redhat.com, LVM2 development <lvm-devel@redhat.com>
Cc: dm-devel@redhat.com
Subject: Re: Default low water mark threshold for a new thin pool
Date: Tue, 05 Feb 2013 22:26:15 +0530	[thread overview]
Message-ID: <87boby1yz4.fsf@in.ibm.com> (raw)
In-Reply-To: <20130205121846.GB3082@raspberrypi>

thornber@redhat.com writes:

> On Tue, Feb 05, 2013 at 02:30:00PM +0530, M. Mohan Kumar wrote:
>> 
>> Hello,
>> 
>> We are adding a lvm2api for creating a thin pool. During thin pool
>> creation if user does not specify anything for the low water mark
>> thresold, it would result in 0 and no events will be generated when thin
>> pool capacity is reaching its full size.
>
> An event will be generated.
Yeah, I missed that. But if thin pool is consumed fully there is no
enough time to resize the pool and it may result in unwanted scenario?

>
>> I am not sure what should be the default low water threshold
>> percentage. Is there any recommended value for low water threshold value
>> in dm thin pools?
>
> It's very hard to say since it depends on your use case.  In general
> you want to allow dmeventd plenty of time to extend the pool before
> you run out of space.  So if you're seeing a _peak_ provisioning rate of
> 100meg a minute, I'd set the lwm to about 100meg.  It would be nice if LVM
> could help you through this process.

Do you mean mesaure how much MB/blocks dm-thin is able to provision in a
minute and treat it as the default lwm blocks?

>
> - Joe
>
> --
> lvm-devel mailing list
> lvm-devel@redhat.com
> https://www.redhat.com/mailman/listinfo/lvm-devel

--
lvm-devel mailing list
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WARNING: multiple messages have this Message-ID (diff)
From: M. Mohan Kumar <mohan@in.ibm.com>
To: lvm-devel@redhat.com
Subject: Default low water mark threshold for a new thin pool
Date: Tue, 05 Feb 2013 22:26:15 +0530	[thread overview]
Message-ID: <87boby1yz4.fsf@in.ibm.com> (raw)
In-Reply-To: <20130205121846.GB3082@raspberrypi>

thornber at redhat.com writes:

> On Tue, Feb 05, 2013 at 02:30:00PM +0530, M. Mohan Kumar wrote:
>> 
>> Hello,
>> 
>> We are adding a lvm2api for creating a thin pool. During thin pool
>> creation if user does not specify anything for the low water mark
>> thresold, it would result in 0 and no events will be generated when thin
>> pool capacity is reaching its full size.
>
> An event will be generated.
Yeah, I missed that. But if thin pool is consumed fully there is no
enough time to resize the pool and it may result in unwanted scenario?

>
>> I am not sure what should be the default low water threshold
>> percentage. Is there any recommended value for low water threshold value
>> in dm thin pools?
>
> It's very hard to say since it depends on your use case.  In general
> you want to allow dmeventd plenty of time to extend the pool before
> you run out of space.  So if you're seeing a _peak_ provisioning rate of
> 100meg a minute, I'd set the lwm to about 100meg.  It would be nice if LVM
> could help you through this process.

Do you mean mesaure how much MB/blocks dm-thin is able to provision in a
minute and treat it as the default lwm blocks?

>
> - Joe
>
> --
> lvm-devel mailing list
> lvm-devel at redhat.com
> https://www.redhat.com/mailman/listinfo/lvm-devel



  reply	other threads:[~2013-02-05 16:56 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-02-05  9:00 Default low water mark threshold for a new thin pool M. Mohan Kumar
2013-02-05  9:00 ` M. Mohan Kumar
2013-02-05 12:18 ` thornber
2013-02-05 12:18   ` thornber
2013-02-05 16:56   ` M. Mohan Kumar [this message]
2013-02-05 16:56     ` M. Mohan Kumar

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