On 05/24/2010 12:41 PM, Les Mikesell wrote:
> On 5/24/2010 6:56 AM, Robert Nichols wrote:
>>
>>>
>>> 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."
>
> I booted a RHEL6 beta DVD in rescue mode, but it wasn't any better.
> That version of fdisk does show:
> Logical/Physical Sector size 512 bytes
> though, so it's probably hopeless. Oddly, that version of fdisk
> wouldn't let me move the beginning back below 63 either - but I did that
> with the 5.x fdisk.
The only other thing I can think of to try would be to use 'dd' with a
blocksize that is a multiple of 4K directly into a raw partition located
at each of the 8 possible alignments and see if any of them gives
better throughput. I suppose it's possible that something in the USB
bridge chip (guessing that the enclosure presents a USB interface) won't
allow the 4K write to pass. Any chance of experimenting with one of
those drives hooked directly to an SATA port?
--
Bob Nichols "NOSPAM" is really part of my email address.
Do NOT delete it.
_______________________________________________
CentOS mailing list
CentOS@xxxxxxxxxx
http://lists.centos.org/mailman/listinfo/centos
