SATA problem

[Christopher Browne]

On Mon, Apr 4, 2011 at 1:04 PM, Lennart Sorensen
<lsorense-1wCw9BSqJbv44Nm34jS7GywD8/FfD2ys at public.gmane.org> wrote:
> On Mon, Apr 04, 2011 at 12:57:31PM -0400, Christopher Browne wrote:
>> I wound up picking this up, and, after a certain amount of fighting
>> with cabling, got it all working.  Hurrah, 3.7TB free :-).
>
> I am currently using one of these:
> http://www.canadacomputers.com/product_info.php?cPath=14_207&item_id=032449
> along with 4 1.5TB WD black drives.
>
> # parted /dev/sdb print
> Model: ATA H/W RAID5 (scsi)
> Disk /dev/sdb: 4501GB
> Sector size (logical/physical): 512B/512B
> Partition Table: gpt
>
> Number  Start   End     Size    File system  Name   Flags
>  1      17.4kB  4401GB  4401GB               RAID5
>  2      4401GB  4501GB  100GB   ext3         SPARE
>
> Quite useful.

Very interesting array device.  Entertainingly, I have two spare eSATA
ports from that card you suggested, so it would certainly be plausible
to hook up something like this in addition to the two drives I already
added.

Some things not clear from the product...
- It seems like it only gives 1 "line" into one's eSATA bus.  Does
that lose you bandwidth, or does that perhaps not much matter?
- This device "cooks up" the RAID volumes for you?  Or can you access
them as individual drives?  (Actually, found the answer to that: No...
 <http://forum.mediasonic.ca/viewtopic.php?f=11&t=321&p=1512&hilit=SU3S2#p1512>)

This is something of a "strike against," as it means my data is
somewhat "held hostage" by the device.

- It looks like it can be configured without needing particular
software on the host that's to connect with it, right?

I see an 8-bay unit that's coming Real Soon Now, which looks quite
interesting too.  Same inherent problems, of course.

>> BTW, I turned the two drives into one grand big BTRFS filesystem,
>> presumably in some equivalent to RAID 0.  I still have two ports left
>> over, so I could presumably add more disks and turn it into RAID 1 or
>> such :-).
>
> No machine I ever build will ever use less than raid1.  Disk failures
> happen, disks are cheap, and I value my sanity and time too much to have
> to do a reinstall and loose data.  There is no excuse.

Reinstall not an issue; I'm using the space assortedly:
a) To play around with new filesystems
b) Bulk storage of noncritical material

If it happens to blow chunks, that won't enormously trouble me.

It's tempting to consider the Mediasonic device, replete with drives,
and at least the "n+1" protection against failure of RAID 5.
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