MSA2050 sparing question

[Gwendling]

Hello,

My msa2050 has 2 virtual pools , with one disk group each :

1 diskgroup on pool A with 9 x 800Gb SSD's (raid 6)

1 disgroup on pool B with 11 x 12Tb SAS drives. (raid 6)

I have a 12Tb not assigned disk ( just available) that want to use as a spare for pool B diskgroup.

With dynamic sparing ( default i think) , will this disk been used for reconstruction on both diskgroup ?

What is the difference to declare this disk as a global spare ?

I don't want this disk to reconstruct a failure of a drive in the SSD diskgroup.

in other words how can i dedicate this disk to the "B" diskgroup

thank's in advance

Gérard

[Shawn_K · Accepted solution]

Hello Gérard,

With the MSA 2050 there is not an option to assign a dedicated spare drive toa disk group or a Pool. By default, you can only assign drives as global spares (dynamic sparing).

However, becuase you have one pool built entirely with SSDs and one pool built entirely with SAS HDDs, the 12TB avaialble drive if designated as a global spare will only reconstruct to the SAS HDDs in Pool B. The SSD HDDs in Pool A are not compatable matches to any SAS HDD and so will not accept that drive as a spare to rebuild too.

If in the future you add a SAS HDD disk-group to Pool A, then any global spare that is a SAS HDD will be accepted as a rebuild candidate for that disk group. The SSD disk group will still not accept a SAS HDD as a reconstruction candidate. You might wish to consider getting another SSD HDD to set as a global spare for your disk group in Pool A to provide redunaancy in case a drive fails or carefully monitor the usage life of your SSDs.

Cheers,

Shawn

[Gwendling]

Thank's Shawn,

Quick and clear answer top !

Just one more question :

would it be better to declare the 12Tb SAS drive as a global spare or let it just availaible ?

thank's

[SUBHAJIT KHANBARMAN_1]

Hello @Gwendling

There two ways to configure spare. One is Global spare and other option is Dynamic spare.

• Global spare. Reserved for use by any fault-tolerant disk group to replace a failed disk.
• Dynamic spare. Available compatible disk that is automatically assigned to replace a failed disk in a fault-tolerant disk group. This option is enabled by default.

When a disk fails, the system looks for a global spare. If it does not find a compatible global spare and the dynamic spares option is enabled, it takes any available compatible disk. If no compatible disk is available, reconstruction cannot start.

So in your case either you configure your 12TB SAS drive as Global spare or let it be as Available but in that case you need to verify if Dynamic spare option enabled or disabled.

Hope this helps!
Regards
Subhajit

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[Gwendling]

Clear for me thank's Subhajit !

Gérard