Primary Storage

True Flash Architecture in IBM DS8870 – 250,000 IOps @ 9 TB / 1U

By Archive User posted Fri May 16, 2014 10:01 AM


Originally posted by: Kimmel

True flash architecture – that means being designed for the purpose of ultra-high performance from scratch, and not being limited by a Device Adapter, or FC-AL shortcomings. If you look at the specs of typical SSDs of today, each single drive could do tens of thousands of IOps, but when it comes to creating a RAID across a small pack of these, then we see the real results. Traditional architectures often also call themselves “flash”, but in fact were just using SSDs and kept putting them behind the same Device Adapters that also serve the HDDs in a storage system.

That was yesterday.  image

The new High-Performance Flash Enclosure (“HPFE”) which has been announced this week (GA 6 June) removes the Device Adapter limit, as it directly connects into the PCIe fabric of the two DS8870 processor complexes (Power servers). All the RAID calculation is already hard-coded within the HPFE itself, which houses two RAID controllers and either 16 or 30 SAS flash cards, of 400 GB each. The arrays come as 6+P RAID-5. The flash card dimension is just a tiny 46 mm (1.8″). The RAID controller is specifically designed to help unleash the performance capabilities of flash-based storage. The RAID controller design combines the technical expertise of IBM research and development resources with the common building blocks from TMS, the recently acquired leader in flash integration. So both the drive-switching  functions of the Gigapacks (that serve the 2.5″ drives) as well as the functions of the Device Adapter pairs have both been integrated together into the chip design of the HPFE.

This ultra-dense flash enclosure  in the DS8870 provides up to 4 times the IOps performance of current 2.5″ SSDs, on the same amount of capacity.

At the same time it is extremely compact. One HPFE is good for 9.1 TB net capacity, and the form factor for this is just 1U. Each Base frame, in a hybrid DS8870 (mixing with HDDs), can host up to 4 HPFEs.

Using an all-flash DS8870 with HPFEs only, we allow up to 8 HPFEs for that purpose, which is up to 73 TB net in full-flash, and we move additional I/O enclosures (host adapters) into the Base frame then.

One HPFE is good for up to 250,000 IOps and up to 3.4 GB/s bandwidth.

The HPFEs are located at the upper left sparing of the frame which had been an empty area before, so given their very compact size of 1U and given that now the disk enclosures can all be used with HDDs, one hybrid DS8870 allows huge capacities for a tiered configuration, and even for a single frame already.

Still want the good old 2.5″ SSDs? Well, we have three types now, 400, 800 and 200 GB capacity for each drive. But check if the HPFE wouldn't give you a better price-performance (and space-usage) design point.

Still want FlashSystem? Ok that may happen. But then it's not a DS8870, which can give you a few PB of capacity with all the advanced functions being in, and the sixth generation of Easy Tier.

– Happy selling –