What to store on fastest storage tier?

[admin]

Hey All,

I have an 8Gb FC SAN with 4 shelves.  Most of the drives are 10K drives, but I have two LUNS of 15K drives.  No SSD's, unfortunately.

I have read a couple of different ideas about what to put on the fastest tier:

• Put the Linked Clone Parent on the fastest tier
  • It would make sense that this would help recompose operations because the replica is being generated based on the master, therefore the master needs the fastest storage.
  • Does this help performance in normal operations?  It seems like recompose would be the main place this helps.
• Put the Linked Clone Replicas on the fastest tier.
  • I don't totally understand this one, because I thought each LUN had to have a replica.
  • Is it really possible to have a LUN without a replica (or a LUN where the replica is stored elsewhere?)
• Redirect disposable disks to fastest tier
  • Maybe I heard this one wrong -- did they mean "any other tier besides linked-clone LUN's"?
  • I can see the benefit to moving disposable disks to their own LUN.

Thanks,
Drew

[mittim12 · Accepted solution]

Depending on your version you can definitely have a LUN dedicated to replicas which means you wouldn't have to have a replica on each LUN where the clones are stored.   If you edit your pool settings and visit the data store option you will see a check box for Use different datastore for OS disk and View composer disk.   Check this and then select your datastore you want to place the replica.     It typically goes in the order below but can be changed to match your environment.

replica                SSD

clones                 FC

Peristent Disk     SATA

Also check out this blog post, http://myvirtualcloud.net/?p=1137

[admin]

Thanks for the reply, that helps a lot!  That blog post is really great.  I have View 4.6.

I don't have SSD or FC drives (I wish!), the best I have are 15K SAS, with the rest being 10K SAS.

So I will try this:

Master: 15K SAS

Replica: 15K SAS

Clones and everything else: 10K SAS.

Thanks!

Drew

[mittim12]

Cool, let us know how it goes.   I wouldn't worry to much about the Master performance as it is only used when your creating a new replica.