A single SSD dedicated to higher tiers PCs and workstation with an eye on the server and datacenter sphere.
In the last years the incredible tecnical evolution has brought the SSD market to a stalemate on a performance side, in the meantime the price of a single Gigabyte sharply lowers.
If the speed peaks obtained in the desktop environment are consolidated, on the other hand there is still space for big improvements in server and datacenter environments where, beside data transfer speed, parameters such as number of IO writings and performance consistency count.
SATA 3 or SAS 6 Gbps disks offer mean sequencial writing and reading speeds close to 550Mb/s but with largely variable results in terms of parallelisms between operations and their temporal duration. Disks that offer large sequencial transferring speeds may be of use on desktop systems or systems that leverage their main utilization on the writing and reading of large dimension files, but in some contexts something different might be necessary.
Indeed, in server and workstation systems it’s quite rare to deal with univocal tranfers of a single, large file; it’s more frequent to deal with numerous and sparse requests by applications and different instances of smaller files placed in different points of the disk by applications or different instances.
A perfect SSD suitable for these environments must be able to fulfill these I/O requests and must have a controller capable of simultaneously handling writing and reading in different points of the device.
Another key point is the duration of the performances through time. The majority of the SSD disks utilizes a provisioning mechanism that organizes the writing requests with the aim of having the best performances possible: when such operations last long, many controllers encounters some difficulties at handling at the same time the quantity of data to be written and the internal reorganization of the resources.
This is the reason why many manufacturers have developed controllers and algorithms dedicated to products for the server and workstation environment, whose maximum speed can be sacrified in the name of data consistency and performances kept at the same level.
Samsung, Intel, Micron and Crucial, which have high end products available that tries to fill this segment of the market, now must face another fierce competitor whose potentialities are huge: Corsair.
By leveraging the decennal experience in RAM archiviation technologies and present on the SSD market since its appearence, Corsair has avoided the shortcuts that have been utilized by other manufacturers that use third-party controllers and memory cells by simply assembling products. Corsair invested on an in-depth sduty to offer product that wouldn’t be swept away by the big giants that own the productive capacity of controlelrs and memory cells (the aforementioned 3-4 manufacturers).
The Corsair SSD line is composed of a good number of products, and in this analysis we will deal with the top line Neutron XT, a disk characterized by excellent performances in desktop systems and, above all, in server and workstation systems with great results.
The disk - Corsair Neutron XT
As we previously mentioned, Corsair has avoided entering in the lap of the manufacturers that basically assemble SSDs with third-party controllers and chips which have been blown away from the actual market.
Corsair too produced disks with SandForce controllers and similars, but it maintened a precise strategy that has brought to the acquisition of Link A Media a couple of years ago and to the development of a sparkling new controller hosted insinde the new Neutron XT disks.
The new controller is called Phison PS3110-S10 and includes some features unique in its genre.
With respect to the previous generation, the leap is right off evident: the controller is equipped with 4 separate cores, 3 of which deals with the internal management of the memories (reading, writing, garbage collection and wear-leveling), while the remaining one takes care of the relations with the external world and gives out tasks.
The controller now supports all the available flash memories, including MLC and TCL which allows an addressing of up to 2TB.
At the moment Corsair offers the Neutron XT in 3 sizes using 19nm Toshiba MLC cells: 240, 480 and 960GB.
The disks are made of 64Gb per die memory cells for the first two sizes, the 960Gb model is made of 128Gb per die memory cells. They obviously are 256, 512 and 1024Gb disks, with the remaining part reserved for the system for the internal advanced management and for wear-leveling.
The controller includes an advanced parity schema that Phison calls Page RAID ECC Parity which is devoted to protect disks from irreversible errors of single NAND cells.
This parity schema uses the portion of the riserved disk space to calculate data parity so that it can retrieve lost data in case of not so serious hardware errors.
We have used a dedicated machine for a complete test in a server/workstation system. In particular, we used an HP DL180 server with two Intel Xeon L5520 Quas Core processors and 24GB of memory.
The controller we utilized is an LSI 9211-8i with SATA 3 support capable of handling solid state disks too.
We used a 240Gb Nuetron XT disk, kindly supplied by Corsair.
Maximum and sequencial performances
The measurement of the maximum performances has been performed with ATTO, a simply software capable of accomlish writings and readings of large files on a well definied partition on the disk.
The Nuetron XT disk, formatted with the NTFS file system, has been analyzed with a command queue of 10, the maximum for this test.
The results are excellent, over 550Mb/s in writing and 532Mb/s in reading in sequencial mode, paired with the maximum speed available through the SATA 3 interface.
From a purely sequencial aspect we evaluated the speed variation with a parallel command queue from 1 to 256 wih interesting results.
With a reduced command queue (so with only one communication channel) the disk offers more than 400Mb/s and more than 500Mb/s with a 4-element queue, too.
The trend is then levelled to great value comprise between 500 and 520Mb/s on the whole analyzed spectrum.
Casual writings and readings
In a purely casual setting the achievable performances are mainly limited by the controller utilized. In the server environment the durability and the data die coerence are preferred, therefore the 90.000 I/Ops indicated by Corsair haven’t been reached.
Anyway, it’s worth to note how a maximum speed of more than 240Mb/s in writing and 280Mb/s in reading with an 8-command queue is reached; the speed behaves linearly as the command queue gets larger.
From an I/Ops standpoint the result is the same, with high values in every condition.
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