How can I differentiate between eSata card & card that uses NVRAM. The specification of card that I've reviewed at this website
http://www.attostore.com/sashostadapter.html do not indicate anything regarding that.
NVRAM = cache + optional battery
Areca and ATTO are both proper cards, and do have NVRAM solutions. The easiest way to determine this, is look for a separate processor and cache, as it's possible that cache can be added to an eSATA controller (though it's not usually done).
The Oxford 936 series is such an example. That chip uses an ARM processor, and the SE verion (capable of RAID 5), also has a bit of cache. But it does NOT have a battery in it. So for it to be capable of dealing with the write hole issue, it needs to be run with a UPS.
But the UPS is really a necessity with any card, including anything by Areca or ATTO. Ideally, you run both the battery and the UPS, but in some cases, such as ATTO, they list a battery they've never produced. And Areca doesn't actually recommend them as being necessary.
Just make sure you've a decent UPS (really a true online unit, which always draws its power off of the batteries = no switching, and is almost always a pure sine wave output due to the better inverter design used).
For sure I will check my system compatibility with the card itself and HDD that can be used with before spending any penny. I am not sure what do you mean by avoiding consumer drives; do you mean I shouldn't update the drive once I install the raid card or I shouldn't install any third party drives?
Areca or ATTO will work in the MP. But you must pay detailed attention to the drives you select (and that includes the drive firmware revision as well, as the earliest versions may not work, and required an update to function - card makers work with drive makers on this).
Consumer HDD's would include models such as:
WD Caviar series
Seagate 7200.xx series
Hitachi Deskstars
Enterprise units:
WD REx (i.e. RE3 or RE4)
Seagate ES.2 series
Hitachi Ultrastars (I recommend avoiding them due to total lack of support in my experience - needed firmware, and I got the run-around from hell)
Any SAS drive.
To be honest I may purchase 3 HDD, and link 2 HD together and keep the third for backup. I believe this may be the perfect combination. I am not going to buy External HDD. I am not sure if that right or wrong but I believe it best option I have right now.
It would certainly work. But please realize that using a card with the internal HDD bays requires an HDD adapter kit in the '09 models that will set you back another $165USD (
here). In the '08 systems, it means you'd likely need an extender cable to get the iPass (SFF-8087) to the card (
here; $75USD, used to be $90USD).
But 2x disks would limit you to either 0 or 1, as you'd need a bare minimum of 3x drives to build a RAID 5.
And if you leave it at 0 or 1, you may not really need to bother with a card (you can use OS X's Disk Utility to create the array). At this point, I'll presume that's not going to be the case for very long.
I am not sure how will I use backup features with RAID; but I will have my third drive for backup. I will figure how do I use RAID backup once I have it; but now I feel it is really hard to speak about details because I do not have any experience about RAID.
The OS and software run under it will see the array as a single logical disk (i.e. Drive Letter: under Windows, Disk n/Partition x under Unix).
Backup software (Time Machine or otherwise), won't have a problem with it. Just select the locations and you're done. But I seriously recommend spending the time to set up the automatic scheduling features.
I live outside US; so I believe that it won't make any differences, expect ARECA may have international number while ATTO have a US only number; which I believe its advantage for ARECA over ATTO in my opinion. Moreover both of them will be responding to mails and that is really fair enough for me.
Either way, you can call, but it will cost you to do so.
Areca's aren't that hard to use, and emails take up to 3 days to obtain a response (time zones have an influence in this). They're also cheaper than ATTO's, and can outperform them (certain models with upgraded cache).
ATTO's are slightly easier to use, but cost more. The time zone issues won't be as bad as it would be for me with Areca I should think. Figure 24 hrs or so for an email response (assuming you can't adjust your schedule to be active during US East Coast business hours).
As per enclosures, there's also Enhance Technologies (
E8-MS or
E800MS) and Sans Digital (
TowerRAID TR8XHA) to consider. They're all basically the same internally, so go with what's cheapest and suits your sense of style (they all offer silver anodized aluminum versions, though they're harder to find in the Enhance branding).
