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?