[rescue] Backups

Phil Brutsche phil at tux.obix.com
Sun Jun 19 21:38:55 CDT 2005

Peter Corlett wrote:
> I built one of these for work the other day using a 3ware 9xxx 
> controller and a pile of 300GB Seagate 7200.8 disks. I get about 
> 120MB/s from the array, which seems to be a limitation of PCI rather 
> than the disks.
> The 7200.8 disks seem to be very much like SCSI disks with a SATA bus
> interface. They have a five year warranty, and support TCQ which is 
> what normally makes SCSI perform better than IDE.

The exact specification that includes TCQ is SATA II. Be *very* careful
when purchasing SATA drives and RAID controllers - there are only 3 or
so drive manufacturers that support SATA II at this point (Hitachi,
Segate, Maxtor). However... you need the *controller* to support SATA II
before any of the advanced SATA II features (like TCQ) can be used.

The number of decent SATA II RAID controllers is much, much smaller than
the number of manufacturers that make SATA II drives. The LSI Logic
MegaRAID 300-8X is the only one I know of: 128MB ECC DRAM, optional BBU
for caching writes, 8 SATA II ports, PCI-X (64 bit + 133MHz,
theoretically 512MB/sec).

The 3ware does not *explicitly* state that the 9x00 cards support SATA 
II. And just because they support SATA II doesn't mean they support TCQ 
- there's more to SATA II than TCQ and a 300MB/sec bus.


Phil Brutsche
phil at tux.obix.com

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