New subject: Question about flash pool maximum SSD size and local tiering

17 Oct 2023


      Hi Florian,
If you have the NL-SAS aggregate in place already I’d recommend having a look at using AWA to figure out what the optimal cache size would be:
https://docs.netapp.com/us-en/ontap/disks-aggregates/determine-flash-pool-ca...
That would give you an idea of how much Flash Pool capacity you’d really benefit from.
Regarding 3.8TB vs 7.6 TB – if the 7.6 TB drives are not listed as supported in the HWU, it’s most likely not supported.
There’s also a note in the HWU for the 3.8TB drives under “System Cache Limits”  – “Max number of Flash Pool Data SSDs: 20” (this is excluding RAID parity & hot spares) – if I’m intepreting that note correcly there’d be no point in adding more than one shelf of 3.8TB drives.
Regards, Johan
On 2023-10-17, 09:57, "Florian Schmid" fschmid@ubimet.com wrote:
Hi Sebastian and Michael,
thank you very much for your help.
We haven't bought the SSD shelves yet.
We don't know, if we should take 2 shelves with 3.8 TB or 1 shelf with 7.6 TB.
I tend to one shelf with 7.6 TB...
We are using flash-pool already with Raid-4, exactly for saving space.
My problem is now, that I'm concerned about the HWU statement, that there is no SSD listed for using in flash-pool over 3.8 TB.
This let me think, that flash-pool is not supported for SSD with 7.6 TB or greater.
I haven't found anything else about it on NetApp site, only in the HWU for system cache limits for FAS 8300
Same limits are also for 8700 or 9000 series, no difference here.
Really strange.
Best regards,
Florian
----- Ursprüngliche Mail -----
Von: "Sebastian Goetze" <spgoetze@gmail.commailto:spgoetze@gmail.com>
An: "toasters" <toasters@teaparty.netmailto:toasters@teaparty.net>
Gesendet: Montag, 16. Oktober 2023 15:35:36
Betreff: Re: Question about flash pool maximum SSD size and local tiering
Hi Florian,
On 16.10.2023 15:01, Fenn, Michael wrote:
...
FlashPool SSDs (unlike FlashCache) are attached to aggregates as normal RAID groups, so you can use as many 3.8 TB drives in RAID-DP as you like to hit the maximum FlashPool capacity.
Consider using RAID4 for the SSD RaidGroups... More Cache, and for the
Write-cached blocks, not really less safety. (SSDs are more reliable,
blocks are usually written fairly soon to HDD anyway)
Regarding sizes: any size that's supported for the HW should be fine
(3.8/15.3TB). Within the Cache-RG, you should use the same size disks,
however...
...
Note that FlashPool and FabricPool use the same underlying tiering metadata structures, so you can only have one or the other enabled on any given aggregate.
Thanks,
Michael
On 10/16/23, 8:03 AM, "Toasters on behalf of Florian Schmid via Toasters" <toasters-bounces@teaparty.netmailto:toasters-bounces@teaparty.net <mailto:toasters-bounces@teaparty.netmailto:toasters-bounces@teaparty.net> on behalf of toasters@teaparty.netmailto:toasters@teaparty.net <mailto:toasters@teaparty.netmailto:toasters@teaparty.net>> wrote:
Hi Alexander,
this is a very good tip! Tank you very much.
I will have a look on this.
Best regards,
Florian
----- Ursprüngliche Mail -----
Von: "Alexander Griesser" <AGriesser@anexia.commailto:AGriesser@anexia.com>
An: "Florian Schmid" <fschmid@ubimet.commailto:fschmid@ubimet.com>, "toasters" <toasters@teaparty.netmailto:toasters@teaparty.net>
Gesendet: Montag, 16. Oktober 2023 12:07:53
Betreff: AW: Question about flash pool maximum SSD size and local tiering
Hi Florian,
I cannot answer the question with the SSD sizes, I'm not sure if this is really a hard requirement or if the slices just may not be bigger than 3.8TB (in that case, you could probably manually partition the SSDs), maybe someone else has more insights into this.
As for your second question: You can spin up OnTap's integrated S3 server on your old boxes and use them as fabric pool targets:
https://www.netapp.com/media/17219-tr4814.pdf
Best,
Alexander Griesser
Head of Systems Operations
ANEXIA Internetdienstleistungs GmbH
E-Mail: AGriesser@anexia.commailto:AGriesser@anexia.com
Web: https://www.anexia.com
Anschrift Hauptsitz Klagenfurt: Feldkirchnerstraße 140, 9020 Klagenfurt
Geschäftsführer: Alexander Windbichler
Firmenbuch: FN 289918a | Gerichtsstand: Klagenfurt | UID-Nummer: AT U63216601
-----Ursprüngliche Nachricht-----
Von: Florian Schmid <fschmid@ubimet.commailto:fschmid@ubimet.com>
Gesendet: Montag, 16. Oktober 2023 11:53
An: toasters@teaparty.netmailto:toasters@teaparty.net
Betreff: Question about flash pool maximum SSD size and local tiering
Hi,
I have checked NetApp HWU for a FAS 8300 and system cache limits.
Ok, so far, max flash-pool is 72 TB, which is a way more than I want to use, but I haven't seen usable SSDs greater than 3.8 TB.
Is that really true, that I can't use a 7.6 TB or 15.3 TB SSD for flash-pool?
It would be nice, if someone has here a deeper understanding than I have about this and can give me here some clarifications.
May I ask a second question?
Is flash-pool still the way to go for speeding up NL-SAS aggregates?
I had a look on fabric-pool tiering, but it seems like, that this only works to S3 storage, which we don't have.
We have plenty of NL-SAS storage and also of SSDs and it would be great to have a tiering between them or at least use them for caching.
Best regards,
Florian

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Re: Re: Question about flash pool maximum SSD size and local tiering