Nimble Expansion Shelf burn test

[Hafizul_Aslam]

@Vipin_S 

based on figure below, I have 11 * 1TB HDD to be inserted. Is it the cache capacity is sufficient. I also have 4 * 480GB cache SSD on hand. do i need to upgrade the cache also? May i know the procedure to replace cache SSD even cache SSD in a healthy state?

[Vipin_S]

Before you install the new drives:
• If your array does not have the minimum SSD cache capacity, you must upgrade the cache before proceeding with
the HDD upgrade. Refer to the below Cache Upgrade Guide for your array.
https://infosight.hpe.com/InfoSight/media/cms/active/public/pubs_Cache_Upgrade_HPE_Alletra_5000__2120__Nimble_Storage_HFxx__ES3.pdf
• For an HPE Alletra 5010H, the minimum SSD cache required to support the 11 x 2TB HDD field upgrade is
1920GB.
• For an HPE Nimble Storage HF20H array, the minimum SSD cache required to support the 11 x 1TB HDD
field upgrade is 1920GB.
• For a model CS1000H Nimble Storage array, the minimum SSD cache required to support the 11 x 1TB HDD
field upgrade is 960GB.

[Hafizul_Aslam]

Hi Vipin,

I want to query with below statement.

Notes: If cache drives being upgraded require removing existing cache, best practice is to replace one SSD drive in a
24-hour period. This is especially recommended for VDI environments workloads that have repetitive requests. Doing
so significantly decreases the impact of performance in the environment.

Does it mean i need to replace 1 cache SSD and wait for 24 hours and then can replace the second cache?

If this is correct, i would require 4 days to replace all 4 cache SSDs.

[Vipin_S]

Hello  Hafizul,
Yes, you got it right.
It is recommended to replace one SSD in one day. As the SSD holds the frequently accessed data, it would impact the system performance if we replaced all SSDs in a single day.
if one SSD is replaced in a 24-hour window the Nimble OS will intelligently manage the hot data and lessen the performance impact.
Let me know if you have more questions.

[Hafizul_Aslam]

@Vipin_S Hi Vipin,

There is no downtime require right to replace cache SSD?

Is there any remove button option in GUI to be select first before removing cache sled or it is safe to straight away remove and insert a new cache?

[SanjanaN]

HI Aslam,

You do not have to shut down the array to upgrade the drives.
https://infosight.hpe.com/InfoSight/media/cms/active/public/pubs_Cache_Upgrade_HPE_Alletra_5000__2120__Nimble_Storage_HFxx__ES3.pdf

I have attached here the Guide that gives the procedure for cache upgrade for your reference.