On Tue, Apr 28, 2009 at 10:23 AM, kelsey hudson <khud...@drjays.com> wrote:
> er krishna wrote:
>
>> in the case of SAS, you can basically have 128 fanout expanders and
>> 128 edge expanders per host connector. That gets you 16384 disks per
>> physical SAS connector.
>>
>> >>>> This is clear and thanks for it. But Can SATA hard disks be
>> connected on SAS controller ? I don't hink our AoE will serve with SAS
>> disks. Please confirm it.
>>
>
> AoE can serve out any storage you want. You can serve files, logical
> volumes, raw block devices, you name it. AoE can export any type of storage,
> be it IDE, SATA, SAS, SCSI, Fibre Channel -- AoE doesn't care.
>>>> Its great, I was not aware about it. What my understanding was AoE uses
ATA read/write command which can't be suitable for SAS/IDE/SCSI/FC disks. I
followed the link, & now I think for these non ATA devices there must be a
converter which will convert one protocol into another like SAS to ATA or
IDE to ATA or SCSI to ATA. Please confirm if its like that.
>
>
> SATA hard disks can, in fact, be connected to a SAS controller (but not
> vice versa). They do this using STP, the SATA Tunneling Protocol.
>
> You should read http://en.wikipedia.org/wiki/Serial_Attached_SCSI for more
> information.
>
Ya, I have gone through the link and STP protocol for conversion.
>
> In the case of SATA, you can get a 15-device breakout expander. This
>> expander cannot be cascaded like SAS, so you're limited to 15
>> devices per connector (total).
>>
>> >>> Just asking, here I am not clear. How many connectors I can connect ?
>> Each connector will have 15 disks capacity. Is there any way to connect more
>> than one connectors, what will be the maximum limit according to the
>> available solution in market. I am not concerned about theoretical limits.
>>
>
> You have 15 devices per controller channel when using a SATA expander.
> Thus, if you have a 16-channel SATA controller, you can connect 16 expanders
> with 15 drive connectors each, for a total of 240 disks. If your SATA
> controller has 24 channels, 360 disks. You just need one expander per
> channel.
Understood clearly & heatiest thanks for it. Can you please tell me some
links/urls from where I can get reliable SATA expander and SATA controller
(like 3ware).
>
>
> Note that expanders are not common, and, as I said, work poorly with Linux.
> So, if you do manage to get your hands on one, make sure you're using a
> hardware RAID adapter.
>
>
>>> So, this is due to x86 interrupt handling problem & RAID adapter is
solution against this. Please confirm.
And really very much thankful to you for all the helping hand and
suggestions from your side.
Thanks & Best Regards,
Krishna
>
> Regards,
>
> --
> Kelsey Hudson
> Sr. Systems Administrator, DrJays.com
> 9180 Camino Santa Fe, San Diego, CA 92121
> 888.437.5297x134 (desk) 619.852.6374 (cell)
>
>
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