By including cache memory, the current 3ware top model settles with one of the shortcomings that earlier 3ware adapters were suffering. In its default configuration, the new Escalade 9500 series is shipped with 128MB cache. The cache memory is provided by means of a 144-pins SO-DIMM module, which can be replaced by memory modules with a maximum capacity of 1GB. At the moment 512MB is the limit because 1GB SDRAM SO-DIMMs are scarcely available. An optional battery backup unit (BBU) prevents the loss of data in the write-back cache when a power failure occurs.
The hardware implementation of the Escalade 9500S largely remained the same compared to its predecessor. The SRAM chips could be omitted because the SO-DIMM is also used for RAM. A NEC V850E microcontroller is residing on the back of the PCB, opposite to the location of the SO-DIMM slot at the frontside of the board. 3ware still uses its in-house ATA/133 controllers. These chips, named 200-0033-00, are now in use for several years. Native Serial ATA is still lacking in the design, and it seems a native Serial ATA solution won't be appearing in the near future. Last September 3ware and Marvell demonstrated a SATA/300 bridge chip at the Intel Developer Forum.
Besides the 8-port version, which will be tested in this article, 3ware provides models with four and twelve ports. The eight and twelve port versions are available in ML versions supporting multi-lane connections. 3ware has developed its own solution to combine four Serial ATA-ports in one InfiniBand connection, so that the number of cables can be reduced four times. A chassis with a multi-lane backplane is required to use multi-lane cables.
According to 3ware, the Escalade 9500S-8 is capable of reaching 400MB/s sequential transfer rates on read operations, and write operations can be processed with transfer rates exceeding 100MB/s. Nothing bad can be said about the read transfer speeds, however writing speeds of 100MB/s are not impressive at all. Using current generation 7200rpm drives, even a small RAID 5 arrays consisting of three disks have the ability to reach transfer rates of in excess of 120MB/s.
3ware's featureset has made a considerable jump forward in the Escalade 9500S series. Support for RAID 50, adapter teaming, and 64-bit LBA have been added. 3ware is promising the addition of online capacity expansion and online RAID level migration in future firmware updates. With those extensions the featureset of 3ware's RAID software stack would reach the enterprise level. The firmware update has been in the pipeline for quite some time now, but so far has not been delivered. According to the original roadmap, online capacity expansion and online RAID level migration were planned for the summer of 2004. The driver support for the Escalade 9500S is similar to the Escalade 8506; pretty good.
A very irritating feature of the Escalade 9500S-8, which nagged us horribly during testing, was the habit of this adapter to lock hard disks, as a result of which they could no longer be used by other controllers. There are two ways to make the hard disk accessible for other controllers. The first way is to reconnect the drive to the Escalade 9500 and configure the drive as a single disk in the management tool. The second method of unlocking the drive is by using the obscure hotkey -r in the management tool. Although putting a lock on the disks helps preventing the disk to be written by accident there is also a potential danger: if the Escalade or the array fails, it won't be possible to reconstruct the data on the array by using recovery tools on a system with a non-3ware controller. We would prefer not to have the locking feature. It can be really frustrating for the user, especially because you can only learn about the existence of this 'feature' by reading the manual. We all know that most users only read manuals after a problem arises. In our case, we were hinted about the existence of the locking feature in an appendix to the RAIDCore BC4852 manual.
The webbased managment interface is simple and effective by design. Similar to its predecessor, the Escalade 9500S-8 comes with a firm price tag. Only by exchanging ¤ 600,00 one can become the owner of this card.