SATA RAID: Adaptec 1420SA, Promise TX4300?

[Matthias Andree]

Tenebrae <tenebrae_bsd at niceboots.com> writes:

> I'm interested in this "newfangled" serial ATA stuff I've been hearing
> about (heh) and thought I might try my hand at getting a RAID1 mirror
> going on for my home dirs.  Sadly, I have no experience with RAID.
> I had initially planned on just setting up two identical drives and using
> one to periodically back up the data, but have been told RAID1 is a better
> way to do this.  Now I need to figure out what type of controller card to
> get and was hoping for some input on affordable cards.

RAID1 is _not_ a backup, but an availability aid.
If going for RAID1, be sure to add a backup solution.

Simple scenario:

If you type "rm", your files are gone from both disks with RAID1.

With regular synching, even without versioning files, you have time
until the next synch operation to retrieve accidentally deleted files.

With real backups, the deleted files will be available for longer.

> I was looking at the Adaptec Serial ATA II RAID 1420SA and Promise
>FastTrak TX4300 4-port SATA RAID PCI adapters.  I did find a note on
>the Promise card that it is now supported in Current.  Is this
>something that might make its way into the 6.x-STABLE branch at some
>point?  Also, I have heard that there is "bad blood" of some sort
>between Adaptec and FreeBSD.  I am not interested in a flame war
>ensuing, but if there is limited to no support, I'd like to know so
>that I can avoid their cards.

Forget both cards. Neither of the two is hardware RAID, see:

http://www.brentnorris.net/blog/?p=158
http://linuxmafia.com/faq/Hardware/sata.html

Cheating people and selling software RAID cards where the BIOS or driver
has to do the mirroring has become quite popular with SATA "RAID".

Be sure to get something that is real hardware RAID.

You don't need to pay for software RAID, you usually get that for free
with the onboard chipset these days.

BTW, does FreeBSD 6.1 support the ICH7-R already? 6.0 did not.

>Hopefully those two cards give an idea of the price range and
>requirements of the cards I'm looking at: 4 ports for future expansion,
>around $150 US (or less),

No way. Real RAID costs more than twice as much for 4 ports. 150 bucks
suffice only for the 2 port warm-plug (i. e. you need to manually mark
the drive for removal in the software or BIOS, then exchange it , then
manually start the rebuild operation in software or BIOS)
3Ware (now AMCC) Escalade 8006-2LP.

This is quite a long card, it doesn't fit the LP slot in the
Fujitsu-Siemens Primergy RX100S3 because the humongous CPU cooler gets
in the way.  So check the dimensions before ordering anything.

FreeBSD's driver for the AMCC/3Ware/Escalade 5000 - 8000 series is
twe(4), the newer 9500 series adaptors are supported by the twa(4)
driver, and the driver for the better MegaRAID SATA cards is amr(4).

I don't know though which of these have working FreeBSD
monitoring/administration utilities, I'm using Escalade 8000 and
MegaRAID SCSI with Linux.

>low profile PCI for a rack-mount case.  Are either of these two cards
>supported in FreeBSD 6.x-STABLE?
>
> If it makes any difference, I plan to buy a pair of these drives for it:
> Maxtor DiamondMax 10 300GB Hard Drive 6V300F0, Serial ATA 3.0Gb/s, 7200
> RPM, 16MB Cache.

Are you fixed on Maxtor? Personally, I'd prefer Samsung, Seagate,
Western Digital (in alphabetic order).

Note that some better real Hardware RAID cards have one controller per
SATA channel, there it doesn't actually matter if you get a SATA-I
drive/controller or a SATA-II drive for those, you aren't going to max
out 1.5 Gb/s with any drive, not even the newer Raptors.

If you want NCQ, check if the controller supports it, or forget about
NCQ and get a controller with battery backup unit (rare with SATA) and
use copyback (writeback) caching.

But don't ever dare use write caching without at least a dedicated UPS:
the corruption patterns of UFS with write caches on are extremely
destructive, been there, seen that -- with a test machine and only a
small 2 MB on-drive write cache.

-- 
Matthias Andree