Stop, NetApp, You’re Killing Me

Andy — Tue, 05 Feb 2008 15:15:15 +0000

I’ve recently bumped into a couple painful limits of Data ONTAP. The first is the widely-known 16TB limit on aggregate size – with each day, it’s increasingly stunning to me that they haven’t increased this yet: 16TB is big, but it just isn’t that big any more. Just as painful is the much less discussed limits on A-SIS volume size – for the 2020 we just purchased, it’s 0.5TB, which caught us by surprise. Our reseller – who forgot to mention the A-SIS limit to us before we purchased the filer – claims that this limit will be at least doubled in ONTAP 7.3; 1TB is still lame.

We purchased the 2020 as a backup-to-disk device with two shelves of 750GB drives; when those 750GB drives shrink to the 621GB that’s actually usable from each to create an aggregate, we’re left in an uncomfortable position. We can create a 16TB aggregate but awkwardly have only a few drives left over that would either go unused or could be made into a really small aggregate. Or, we could guess what the best strategy to split the shelves up into two mid-sized aggregates would be – and hope we don’t paint ourselves into a corner later with this strategy. (The 2020 has a maximum of two external shelves – we’d have to head swap to a 2050 or better to add more.)

Since this is a backup-to-disk machine, A-SIS seemed a great fit for it, and we happily paid the license. Only now, we’re finding out that the largest volumes (or qtrees) we have – where we’d see the most benefit from A-SIS – can’t be deduplicated. I guess we should just consider this another case of the storage overhead tax that NetApp extracts – your 750GB drives become 621GB drives, your large volumes can’t be deduplicated, etc. I really hope that there’s a reasonable technical reason for the A-SIS limitation, and that it isn’t just to prop up NetApp’s margins through tough times by forcing their customers to buy more drives.

Unsolicited advice to NetApp: Quit suing Sun, stop spending time benchmarking EMC gear (as if anyone takes NetApp’s results on EMC seriously), get focused on fixing the problems in your own products and actually help your customers out for a change.

thinking sysadmin » deduplication

Stop, NetApp, You’re Killing Me