Re: [zfs-discuss] Mixing different disk sizes in a pool?

2010-12-18 Thread Tim Cook
On Sat, Dec 18, 2010 at 4:24 PM, Ian D  wrote:

> > The answer really depends on what you want to do with
> > pool(s).  You'll
> > have to provide more information.
>
> Get the maximum of very random IOPS I get can out of those drives for
> database usage.
> --
>
>
Random IOPS won't max out the SAS link.  You'll be fine stacking them.  But
again, if you have the ports available, and already have the cables, it
won't hurt anything to use them.

--Tim
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Re: [zfs-discuss] Mixing different disk sizes in a pool?

2010-12-18 Thread Ian D
> The answer really depends on what you want to do with
> pool(s).  You'll 
> have to provide more information.

Get the maximum of very random IOPS I get can out of those drives for database 
usage.
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Re: [zfs-discuss] Mixing different disk sizes in a pool?

2010-12-18 Thread Ian Collins

 On 12/18/10 10:49 AM, Ian D wrote:

I have 159x 15K RPM SAS drives I want to build a ZFS appliance with.

75x 145G
60x 300G
24x 600G

The box has 4 CPUs, 256G of RAM, 14x 100G SLC SSDs for the cache and a mirrored 
pair of 4G DDRDrive X1s for the SLOG.

My plan is to mirror all these drives and keep some hot spares.

My question is:  should I create three pools (one for each size of drives) and 
share the cache and slog among them or should I create a single pool with them 
all?

The answer really depends on what you want to do with pool(s).  You'll 
have to provide more information.


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Ian.

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Re: [zfs-discuss] Mixing different disk sizes in a pool?

2010-12-18 Thread Tim Cook
On Sat, Dec 18, 2010 at 7:26 AM, Ian D  wrote:

> Another question:  all those disks are on Dell MD1000 JBODs (11 of them)
> and we have 12 SAS ports on three LSI 9200-16e HBAs.  Is there any point
> connecting each JBOD on a separate port or is it ok cascading them in groups
> of three?  Is there a bandwidth limit we'll be hitting doing that?
>
> Thanks
>
>
It's fine to cascade them.  SAS is all point-to-point.  I strongly doubt
you'll hit a bandwidth constraint on the backend, especially if you have the
shelves multipathed, but if that's a concern you will get more peak
bandwidth putting them on separate ports.

--Tim
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Re: [zfs-discuss] Mixing different disk sizes in a pool?

2010-12-18 Thread Ian D
Another question:  all those disks are on Dell MD1000 JBODs (11 of them) and we 
have 12 SAS ports on three LSI 9200-16e HBAs.  Is there any point connecting 
each JBOD on a separate port or is it ok cascading them in groups of three?  Is 
there a bandwidth limit we'll be hitting doing that?

Thanks
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[zfs-discuss] Mixing different disk sizes in a pool?

2010-12-17 Thread Ian D
I have 159x 15K RPM SAS drives I want to build a ZFS appliance with.  

75x 145G
60x 300G
24x 600G

The box has 4 CPUs, 256G of RAM, 14x 100G SLC SSDs for the cache and a mirrored 
pair of 4G DDRDrive X1s for the SLOG.

My plan is to mirror all these drives and keep some hot spares.

My question is:  should I create three pools (one for each size of drives) and 
share the cache and slog among them or should I create a single pool with them 
all?

I'm thinking of creating a single pool to get maximum IOPS early on, even tho I 
understand that once I'll have filled the 145G drives I'll end up having 
smaller stripes and less performances.

Would you do the same?  Is there any reason not to do that?

Thanks
Ian
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