Dell has launched a new range of products – the PS6210 series – at the top end of its EqualLogic iSCSI SAN family....
It includes for the first time an all-flash array, while there are also hybrid flash, fast disk-only and bulk storage variants.
The PS6210 family replaces the existing PS6110 range, and all the new hardware benefits from an upgraded multi-core Broadcom Netlogic XLP CPU in the controllers, a quadrupling of RAM to 16GB per controller and double the number of 10Gbps ports.
Meanwhile, the EqualLogic operating system – EqualLogic Array Software – has undergone an upgrade to version 7, with 64-bit capability, a new GUI and streamlined management of multiple arrays made easier.
The combination of upgrades to array hardware and software leads Dell to claim its best performance figures for any EqualLogic array to date.
These include a three times boost in IOPS and a maximum I/O rate of 1.2 million IOPS, though there are some major caveats to these figures – namely they are read-only and were benchmarked by Dell on using eight PS6210XS hybrid flash arrays.
The PS6210 models
PS6210E, which aims at bulk storage with up to 96TB capacity in nearline-SAS drives
PS6210S all-flash array, with capacity up to 19.2TB in SSDs of 400GB or 800GB
Fast disk PS6210XV in 2.5in and 3.5in 15,000rpm SAS variants, with 7.2TB and 14.4TB capacity respectively
Bulk/speed trade-off of the PS6210X, with capacity of up to 28.8TB of 10,000rpm SAS 2.5in drives
PS6210XS hybrid flash array, which can house up to 26TB of 2.5in SSDs and 10,000rpm SAS drives
The quoted IOPS rates apparently put the EqualLogic arrays in the same ballpark as the speediest of currently existing flash array products from other big six storage suppliers such as EMC, Hitachi Data Systems and IBM.
But the figures quoted are for eight PS6210XS devices strung together, which indicates the IOPS rate for one PS6210XS equates to 1/8 of one million – 125,000 IOPS each. Also, the figures are for read-only operations. Reads are always speedier than writes in flash because writes must erase existing data before writing new information to flash cells.
In the publicity for the PS6210 announcement Dell chose to publicise maximum performance figures for the XS variant hybrid array rather than the all-flash version. Normally all-flash arrays offer better I/O and latency performance than hybrid arrays, simply because they throw more flash at I/O.
This begs the question, is the hybrid XS version with flash and disk quicker because tiering software ensures hot data resides in optimum locations while the all-flash S version has its data less accessible for some reason?
Either way, it seems to mean the IOPS rate for a single PS6210, whether all-flash or hybrid, is not exactly earth-shattering.
More on flash storage
With this announcement Dell has brought its EqualLogic iSCSI range up to match its Compellent family in providing all-flash capability. This year it upgraded its Dell Compellent Storage Center OS to version 6.4 and announced an all-flash Compellent array, the Flash Optimised Solution.
The Flash Optimised Solution comprises SLC and MLC drives in one of its SC220 expansion enclosures. Dell says it will get 300,000 IOPS for this mixed SLC/MLC bundle. That figure is quite low for a flash array, especially one with SLC drives, and suggests Dell has not optimised Storage Center to deal with the tasks involved in managing flash memory.
Instead, Dell focuses on the use of auto-tiering to try to get the most from flash in Compellent, moving data at sub-LUN level, with different parts of the same LUN living on different classes of storage media. That might be an approach it has applied to EqualLogic.