The linear read speeds are the same for both file systems, so we will show you just one general diagram here:
The linear read speed depends linearly on the number of the drives, so RAID0 arrays of two and three devices show twice or three times the speed of the single drive. RAID0 array of four disks doesn’t keep this tendency on, unfortunately. We could either blame the low performance of the central chip or the lack of bandwidth of the PCI 64/33MHz bus.
Unlike the situation with 3Ware 7850 controller, the linear read speed of the N-disk RAID5 array is not analogous to that of (N-1)-disk RAID0 array. The dependence of RAID5 speed on the quantity of the disks is evident, but it is not 4:3. RAID1 array is slower at linear reading than the single drive, while RAID10 falls behind RAID0 of two HDDs. It looks like TwinStor technology (it provides higher read speed from a “mirror” array due to intellectual alteration of the read requests to both drives of the mirror couple) doesn’t provide any advantages in linear reading on the 8500-8 controller.
The linear read speed doesn’t depend on the lazy write status. Well, that’s reading after all!
For the most meticulous sirs (and ladies!), I would like to offer the linear read graphs for every array:
- JBOD (1 HDD) - Graph;
- RAID1 (2 HDDs) - Graph;
- RAID0 (2 HDDs) - Graph;
- RAID0 (3 HDDs) - Graph;
- RAID5 (3 HDDs) - Graph;
- RAID0 (4 HDDs) - Graph;
- RAID5 (4 HDDs) - Graph;
- RAID10 (4 HDDs) - Graph.
3ware 8500-8 Escalade controller left a lasting good impression as it went with waving banners through our tests. Of course, there are minor problems you have to put up with. For example, TwinStor technology is not always correct, and, just like with 3Ware 7850 controller, we have no support for PCI 64bit/66MHz, which is critical even for the four-channel version of the controller if you use modern hard disk drives.
Anyway, this one showed most stable and predictable results among all SATA RAID controllers we have tested so far. We will learn soon if its supremacy is for long. Stay tuned!
You can always find the driver package for 3ware 8500-8 Escalade controller on the manufacturer’s website.
When I was working on the review, version 7.7.0 of the package was already available. This set of firmware, drivers and utilities works in Windows 2003/XP/2000, SuSE Linux 8x, Red Hat Linux 8x and 9x, and FreeBSD 4.8 Beta. By the way, this is the only driver release for Escalade 8500 to support FreeBSD.
Previous versions of the driver set support older operation systems. For example, the 7.6.3 release we used in our tests supports Red Hat 7x and SuSE 7x, but doesn’t support FreeBSD and Red Hat 9x. Overall, it’s quite possible to find a driver for 3ware Escalade 8500 controller that would support the particular OS you use.