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1758
June 23rd, 2012 23:00
Meta luns
1) I need to provide a capacity of 1tb of Raid 5.So which will be the best way creating metas of 500+500 or creating 250+250+250+250 or the last option 1TB single lun.Which will give me best perfromance
2) Suppose i give a meta lun which will be striped ...and our host team concats that lun so stripe from storage and concat from host will cause a performance or not ????
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AnkitMehta
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June 24th, 2012 01:00
LUN Expansion is the process of creating a metaLUN Stroage object. An expansion is similar to a FLARE LUN bind. The component LUNs are joined to the base LUN to create a larger logical storage object. LUN Expansion does not create a new physical storage object. To a host, this new logical stroage object (the metaLUN) appears as the original base LUN (you will see unallocated space one you expand a LUN), except with additional storage capacity.
FYI: The number of metaLUNs that may be created on a CLARiiON is dependent on the CLARiiON model, and secondarily on the storage system's FLARE OS revision.
There are 2 methodes of LUN expansion :
- Concatenation
- Striping
If you are expanding the LUN with Concatenation method the componenet LUN will be available immediately with out any performance impact. However, if you use Striping it will ethe data across and it does have some sort of performance until the data is restriped and then it will take it as 1 single lun.
1. If you are going to use concatination I would go with 1TB as it will add 1 single component LUN.
2. huh?! Please, elaborate? If I understood correctly, you will expand a LUN with Striping method on storage system and your host team will concat that LUN from the Host? Are we talking VMWare here? RDM etc..?
If not, please elaborate the second query, if needed.
You can find detailed information about metaLUN concepts in: Whitepaper: MetaLUN Concepts.
AnkitMehta
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June 25th, 2012 08:00
Indeed it is now!
1. Striped.
2. It doesn't matter, whatever happens on the Host will be done by the LVM. If you are facing a performance on a Hardware level there would be an impact For Eg. Disk Contention.(that would be on storage) LVM is just appending the Logical Volume.
gungun9
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June 25th, 2012 08:00
i belive there has been confusion here..Ok let rephrase here.
1)My host team needs 1tb lun of R5 and so is it better to provide concatenate meta lun 0f 250+250++250+250 or striped 250+250+250+250 .
2) My unix solaris team breaks the space allocated by volume manager and uses the space to increase the different filesystem of the server.
So if we provide either the concatenated metalun or striped metalun they will cocatenate it from the solaris end .
So if i provide striped /concatenated meta-lun and host them also concats it to increase their filesystems ...which will give the best perfromance ..i.e providing concatenated meta-lun or striped meta-lun...
hope now my question is clear
gungun9
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July 23rd, 2012 04:00
so i m providing 1 tb striped meta lun and the host concats will that give me performance .i.e array leve striping and then host level concat
OR
if i provide 1 tb stripe and host team gaian stripes ,so doin this will it give me perfromance .
Can you suggest me the best method when we have such situation ???
AnkitMehta
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July 23rd, 2012 06:00
If I am looking for a performance in a long run, I would go with Striping Method.
There are some pre-requisite for Striping method which you can find it here:
http://powerlink.emc.com/km/live1/en_US/Offering_Technical/White_Paper/H1024.1_clariion_metaluns_cncpt_wp_ldv.pdfWhite Paper: EMC CLARiiON MetaLUNs — A Detailed Review
When you ch0ose Striping method, initially it will have a performance impact as data will get striped across the Base Lun and Component LUN, once the re-striping process is completed. You should notice the better peformance.
So in conclusion, for performance: Expand a LUN with Striping method on the Storage System and Concat it on a Host with LVM.
Here is a demo video which will guide you How to Expand a LUN:powerlink.emc.com> Home > Support > Product and Diagnostic Tools > CLARiiON Tools > CLARiiON Support Demos > CLARiiON Support Demo: How To Expand a MetaLUN on CX3 and CX4 Storage System