[CentOS] raid resync speed? - laptop drive-

Robert Nichols rnicholsNOSPAM at comcast.net
Mon May 24 11:56:05 UTC 2010


On 05/23/2010 01:57 PM, Les Mikesell wrote:
> Robert Nichols wrote:
>> Another thing to keep in mind is that the SATA spec. only requires the
>> internal SATA connector to withstand 50 insertions.  I picked up some
>> nice acomdata (TM) eSATA housings for the drives (512-byte sectors,
>> thankfully) I use for my offsite backup copies.  The eSATA connector
>> is spec-ed for 50,000 insertions.  My laptop came with a warning about
>> the life of that connector, and I found those ratings mentioned at
>> http://www.serialata.org/technology/esata.asp .
>
> The trayless internal hotswap enclosures claim to be good for 10,000+ insertions
> and I'm using larger ones for the desktop drives I had been using without any
> problems.   I have seen some postings to the effect that I need a newer kernel
> to recognize the 4k sectors besides doing the partition alignment.  Maybe I can
> boot the RHEL 6 beta or a fedora iso and see if they are faster.

Sounds good, unless that 10,000 insertion spec is predicated on spreading
the usage among 200 drives such that no individual drives has more than
50 insertions.  ;-(

BTW, I got carried away typing zeros in that spec. for the eSATA connector.
The right number is 5,000 insertions, not 50,000.

If you want a good write-up on what the kernel developers have to contend
with to handle these 4KiB sector sizes, see
   https://ata.wiki.kernel.org/index.php/ATA_4_KiB_sector_issues

For those with a strong stomach for such things, a nice historical
perspective on the horrors of ever-increasing drive sizes can be found
at http://www.win.tue.nl/~aeb/linux/Large-Disk.html .  Just be sure to
keep the 2004 date in mind when it mentions "recent kernels."

-- 
Bob Nichols     "NOSPAM" is really part of my email address.
                 Do NOT delete it.




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