[CentOS] Re: Anaconda doesn't support raid10

Les Mikesell lesmikesell at gmail.com
Thu May 10 13:41:28 UTC 2007


Andreas Micklei wrote:
> Am Donnerstag, 10. Mai 2007 schrieb Feizhou:
>>> Probably not, but is SATA really much worse then SCSI or SAS?  I did
>>> some testing on a dell PE 2950 of 750GB SATA's vs SAS and SCSI drives,
>>> and the SATA drives seem to be faster at least at first glance.  I don't
>>> have good numbers from the  SCSI tests, but at least for sequantial, I'm
>>> getting a better speed off the SATAs.
>> sequential will be better than SCSI due to the packing on those platters
>> which make up for the lack in rpm. NCQ should even up the random ability
>> of SATA disks versus SCSI drives but that support has only become
>> available lately on Linux and you also need the right hardware (besides
>> the right disks).
> 
> SAS and SCSI really has it's place when you need random access with lots of 
> IOs per second, i.e. Fileserver, Database Server. We upgraded our Fileserver 
> (NFS, Samba) from SATA SW Raid to SCSI HW Raid and the difference is HUGE. 
> One the old system a single user doing a large file copy could bring the 
> system almost to a halt. On the new system you do not even notice if one user 
> does a similar operation. However plugging one of the same SCSI discs into 
> your average PC will not give you much advantage.
> 
> There is also a line of SATA discs that aim for the low-end server market, the 
> WD-Raptors. They spin at 10.000 rpm and give much better random access 
> performance than normal SATA drives. The price point is very attractive 
> compared to SCSI and SAS. Great alternative for a tight budget.
> 
> Here is my favorite site for comparing drives. Has nice background articles 
> too:
> http://www.storagereview.com/

I've always wanted a dollars to dollars comparison instead of comparing 
single components, and I've always thought that a bunch of RAM could 
make up for slow disks in a lot of situations.  Has anyone done any sort 
of tests that would confirm whether a typical user would get better 
performance from spending that several hundred dollars premium for scsi 
on additional ram instead?  Obviously this will depend to a certain 
extend on the applications and how much having additional cache can help 
it, but unless you are continuously writing new data, most things can 
live in cache - especially for machines that run continuously.

-- 
   Les Mikesell
    lesmikesell at gmail.com




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