User defined storage pools with stripe

Question

we are planning to crate a single storage pool pool that consists of 60 x 300GB FC disks. we are plaining to create stripe over all of the 60 disks . Does any one any advice on this configuration

ps : we will use User defined storage pool on cellera (NS40 )

thanks

Message was edited by:
cemd

Rainer_EMC · Answer

Hi,I assume you know that user-defined pools wont do automatic striping.So you need to stripe yourself and put the stripes into the pool.I would do it the very same way that system pools do - i.e. for Clariion it stripes over 4 LUNs balanced across SP's and backend bussesa fuller description is in the AVM manualAbsolutely avoid striping LUNs that are on the same disksAccording to our best-practices striping across more than 4 LUNs (assuming 4+1R5 or 8+1R5) doesnt give you additional performance for one file systemthe easiest way is to use the system pool, create some 'dummy' file systems so that you see how they get striped, write it down and then delete the file systems.then you can use that as guidance to stripe for your user-defined poolshope that helpsRainer

dynamox · Answer

According to our best-practices striping across

more

than 4 LUNs (assuming 4+1R5 or 8+1R5) doesnt give

you

additional performance for one file system

does it mean that i can only get 36 drives behind my
file system ? ( 4 LUNs x 9 drives per RG)

Rainer_EMC · Answer

AVM with system pools wont do more - using MVM you can do however much you like

nandas · Answer

Is there any specific need for going with custom pool? I 'll suggest to keep the system defined pool and use AVM to work while creating file systems, The AVM algorithm is good enough for most of the common NAS requirements.

Simply choose what type of RAID you want to configure - if it is RAID 5 - I'll suggest to go with all (4+1) RAID 5 - so that you get only one storage pool (Clar_r5_performance) to deal with. You may exclude the two LUNs created on the RAID Group 0 (Vault Disks) - out of the pool before creating any file system - this will ensure you are not putting any user data on the vault disks - if you want to do so.

Anyway - Rainer had already provided detailed guidelines for the other option i.e. or custom pools. Also, please get in touch with local EMC Technical person (Preferably your EMC SA or IS) - to ensure you are following the EMC guidelines and supported configuration.

Thanks,
Sandip

Peter_EMC · Answer

According to our best-practices striping across

more

than 4 LUNs (assuming 4+1R5 or 8+1R5) doesnt give

you

additional performance for one file system

does it mean that i can only get 36 drives behind my
file system ? ( 4 LUNs x 9 drives per RG)

No. You can put as many drives behind a FS until one of the limits is meet (16 TB FS size, no more disk possible in the frame ....)

It also means, do not create stripes containing more than 4 Luns in your User defined Profiles.

dynamox · Answer

Peter,if i am after IOPS ..let's say i am doing Exchange implementation and need 10.000 IOPS for database stores (will leave logs out for now). I buy four DAEs with 15 x 15K drives, that will give me roughly 10.000 IOPS ( 60 drives x 180 IOPS). How would i go about carving out this space to make sure my database get as many IOPS as possible ?Thanks

Peter_EMC · Answer

Dynamox,the problem seen in the field for requirements like this is:You need the disk spindles initialy because of the IOs, but you do not need the whole disk space these spindles can deliver. So the initial sizing is 60 disk, but only using a small part maybe 3 TB of disk space on them. Later on, someone is using the 'unused disk space' for additional filesystems, checkpoints ..... and putting additional load on them.Depending on the size of the FS, it does not make sense to stripe across to many luns, because the additional performance win is lost because then more than one FS are sharing the Luns and adding load on them.

Rainer_EMC · Answer

for Exchange you normally would use the white papers and solution guides that have setup info for various user counts (either mix of RAID1 and RAID5 or RAID5)

Rainer_EMC · Answer

for Exchange you would normally scale the building blocks described here:
http://www.emc.com/collateral/hardware/technical-documentation/emc-celerra-ns40-1000-user-storage-solution-for-microsoft-exchange-2003.pdf

dynamox · Answer

i understand what you are saying, i am dedicating 60 drives to a user defined pool based on IOPS i need, not on capacity. It will be dedicated to Exchange only and capacity requirements will not increase. I am just curious how would you go about carving this space out ?

disk>stripe>meta
disk>meta
disk>stripe>slice>meta
disk>slice>stripe>meta

Thanks

dynamox · Answer

thanks Rainer, good starting place although i don't see any discussions on how to actually carve space out in terms of Celerra volume management.

Celerra

User defined storage pools with stripe

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