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SSD SmartCache on multiple Logical drives ?

 
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Occasional Contributor

SSD SmartCache on multiple Logical drives ?

Is the Smartcache option only for just one Logical drive on a Smartarray controller or can you cache multiple using multiple SSD's ?

I have a HPE Smart Array P408e-p SR Gen10 controller with it 2 x 3610 Diskenclosures.

Per Disk enclosure there is 1 SSD and 11 disks in RAID 6 (ADG).

I can create one smartcache enabled Raid Set/logical drive. The RAID 6 diskset is being cached with 1 SSD.

On the second RAID 6 diskset  I can only change the controllers cache size (read/write) and not enable smartcache where I use the second SSD (yes it's available as SSD)

I use the Smart Storage Array config tool from the SPP iso disk which is the same as the graphical from the server itself.

There is a SmartCache license key installed but I don't know if it's limited to one Logical drive ?

BTW this is a proof of concept so the config is not for real world usage just for speed and limitation testing.

 

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Occasional Contributor
Solution

Re: SSD SmartCache on multiple Logical drives ?

I found the limitations. You can create only one cache array on a Smartarray controller. In the GUI tool it will create a logical drive maximizing the space of the cache array for a (spinning) disk to cache so there isn't any space left to cache the next (spinning) disk array.

The ssacli (hpacucli) tool will give you more options to limit the logical cache size on the cache array so there is space for another logical cache volume to cache the next (spinning) disk array.

When you define a size for the cache for the (spinnging) disk be awere there is some overhead involved so if your SSD cache aray has 400GB it will not be all available for use. When you create one cache volume of 200GB there will not be 200GB left, more something like 120GB but it will tell you when you want the next volume if this is to big for the size left over.

Enabling SmartCache:
To create a new SmartCache array for existing data logical drive 1 using the solid state drive 1e:1:10:

=> ctrl slot=1 create type=ldcache drives=1e:1:10 datald=1 size=

The command above creates a new SmartCache array, for example, "array B." Only one SmartCache
array may exist on a controller. This example creates an additional caching logical drive using the existing
SmartCache array for existing data logical drive 2:

=> ctrl slot=1 array B create type=ldcache datald=2 size=

Disabling SmartCache:


To disable SmartCache, you must delete the caching logical drive created when enabling SmartCache. To
determine which logical drive is the caching logical drive, use the command ld all show.

=> ctrl slot=0 ld all show

The results indicate which logical drive is the SmartCache.

=> ld all show

Smart Array P421 in Slot 2
array A
logicaldrive 1 (68.3 GB, RAID 1, OK, cached)
SmartCache array B
logicaldrive 2 (16.0 GB, RAID 0, OK, SmartCache for Logical Drive 1)
Once the SmartCache is identified, you can delete the logical drive, disabling SmartCache.

=> ctrl slot=0 ld 2 delete