On 3/5/07, Anders Norrbring
Right.. I'm actually looking at this http://www.adaptec.com/en-GB/products/sas/raid/SAS-4800/
Has anybody worked with any of the mix and match SATA / SAS controllers? They just seem weird to me, so I don't know what I think. ie. SATA uses the ATA command set. SAS uses the SCSI command set. Both SATA & SAS use the same cabling/voltages I believe, so there should not be an electrical issue, but I just have not seen any reports (good or bad) about controllers that can supposedly talk both ATA and SCSI. In Linux do they use a pure SCSI driver? BTW: 3ware uses a pure SCSI driver even for it s PATA controller line, so I don't have an issue with that, just lots of unknowns from my perspective. Greg -- Greg Freemyer The Norcross Group Forensics for the 21st Century -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org
Greg Freemyer skrev:
On 3/5/07, Anders Norrbring
wrote: Right.. I'm actually looking at this http://www.adaptec.com/en-GB/products/sas/raid/SAS-4800/
Has anybody worked with any of the mix and match SATA / SAS controllers?
They just seem weird to me, so I don't know what I think.
ie. SATA uses the ATA command set. SAS uses the SCSI command set.
Both SATA & SAS use the same cabling/voltages I believe, so there should not be an electrical issue, but I just have not seen any reports (good or bad) about controllers that can supposedly talk both ATA and SCSI.
In Linux do they use a pure SCSI driver?
BTW: 3ware uses a pure SCSI driver even for it s PATA controller line, so I don't have an issue with that, just lots of unknowns from my perspective.
Greg
As I've understood, the Adaptec SAS RAID controllers use the aacraid driver in Linux, which we all have already.. ;) They also provide some extra stuff for their HBAs. But then again, I can be terribly wrong, I haven't used SAS HBAs from Adaptec before, just SCSI. I'm not sure I understand what you mean by "mixing" SAS and SATA? On a SAS HBA, you can hook up SATA drives natively, and SAS drives as well. However, mixing both types of drives on the same channel is asking for problems.. -- Anders Norrbring Norrbring Consulting
On 3/5/07, Anders Norrbring
Greg Freemyer skrev:
On 3/5/07, Anders Norrbring
wrote: Right.. I'm actually looking at this http://www.adaptec.com/en-GB/products/sas/raid/SAS-4800/
Has anybody worked with any of the mix and match SATA / SAS controllers?
They just seem weird to me, so I don't know what I think.
ie. SATA uses the ATA command set. SAS uses the SCSI command set.
Both SATA & SAS use the same cabling/voltages I believe, so there should not be an electrical issue, but I just have not seen any reports (good or bad) about controllers that can supposedly talk both ATA and SCSI.
In Linux do they use a pure SCSI driver?
BTW: 3ware uses a pure SCSI driver even for it s PATA controller line, so I don't have an issue with that, just lots of unknowns from my perspective.
Greg
As I've understood, the Adaptec SAS RAID controllers use the aacraid driver in Linux, which we all have already.. ;) They also provide some extra stuff for their HBAs. But then again, I can be terribly wrong, I haven't used SAS HBAs from Adaptec before, just SCSI.
I'm not sure I understand what you mean by "mixing" SAS and SATA? On a SAS HBA, you can hook up SATA drives natively, and SAS drives as well. However, mixing both types of drives on the same channel is asking for problems..
I'm a newbie with this technology, but AIUI you have a sata/sas connector on the controller. If you connect it to a SATA drive the controller figures it out and all communications uses the ATA command set. OTOH, if instead you connect the connector up to a SAS drive, then the controller figures that out and all communications is with the SCSI command set. So if the aacraid scsi driver is used then for SAS drives, the controller is basically just passing the SCSI commands straight thru, but for a SATA drive the controller is doing a SCSI to ATA translation before sending it out. Again I have nothing bad to say about that, I just don't have any first hand experience and I haven't seen any postings that I can recall. Greg -- Greg Freemyer The Norcross Group Forensics for the 21st Century -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org
On 3/5/07, Anders Norrbring
wrote: Right.. I'm actually looking at this http://www.adaptec.com/en-GB/products/sas/raid/SAS-4800/
Has anybody worked with any of the mix and match SATA / SAS controllers?
They just seem weird to me, so I don't know what I think.
ie. SATA uses the ATA command set. SAS uses the SCSI command set. The way it works (if you're asking what I think you are) is that the drives are SATA and talk to the controller using the ATA defined
Greg Freemyer wrote: protocol. The OS is not involved in this. The controller is then available on the system bus like any other SCSI adapter, indeed they are often compatible with well-supported models. SCSI instructions (not sure of the formal name) sent to the controller are then mapped to ATA instructions (same here) for the hard drives, but the OS plays no part in this mapping, it is all done by the card. Hope that clears it up. Russell Jones -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org
Russell Jones wrote:
The way it works (if you're asking what I think you are) You weren't: 3/10 for reading comprehension :-( I'll try again.
Had a look at the wikipedia, usually a good start for this sort of thing http://en.wikipedia.org/wiki/SATA Interestingly it seems SATA II is the name of a standards body, not a standard http://www.sata-io.org/namingguidelines.asp The following is very interesting, as it would seem to apply to all SAS adapters, potentially:
How does SAS compare to other serial technologies, like SATA?
Serial Attached SCSI is an ideal I/O interface for server storage applications. *The SAS protocol supports SAS disk devices and also includes support for the Serial ATA II protocol [!] and command set*, offering customers the flexibility to directly connect both high performance SAS disk drives and high capacity low cost SATA disk drives to the same SAS controller. This added flexibility makes it easy for companies to standardize on a single I/O infrastructure for both mission critical storage and secondary storage dependent solely upon the disk drives installed. Customers can standardize on a single I/O controller or storage system for all of their storage configurations reducing training and repair costs.
http://www.adaptec.com/en-US/products/sas/raid/SAS-4805/_details/4800_4805_f...
So it sounds like the specifiers of SAS made SATA 3Gb/s a subset. If that's so, I guess a SATA drive can be treated as a (less sophisticated) SAS drive. -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org
On 3/6/07, Russell Jones
Russell Jones wrote:
The way it works (if you're asking what I think you are) You weren't: 3/10 for reading comprehension :-( I'll try again.
Had a look at the wikipedia, usually a good start for this sort of thing http://en.wikipedia.org/wiki/SATA
Interestingly it seems SATA II is the name of a standards body, not a standard http://www.sata-io.org/namingguidelines.asp
The following is very interesting, as it would seem to apply to all SAS adapters, potentially:
How does SAS compare to other serial technologies, like SATA?
Serial Attached SCSI is an ideal I/O interface for server storage applications. *The SAS protocol supports SAS disk devices and also includes support for the Serial ATA II protocol [!] and command set*, offering customers the flexibility to directly connect both high performance SAS disk drives and high capacity low cost SATA disk drives to the same SAS controller. This added flexibility makes it easy for companies to standardize on a single I/O infrastructure for both mission critical storage and secondary storage dependent solely upon the disk drives installed. Customers can standardize on a single I/O controller or storage system for all of their storage configurations reducing training and repair costs.
http://www.adaptec.com/en-US/products/sas/raid/SAS-4805/_details/4800_4805_f...
So it sounds like the specifiers of SAS made SATA 3Gb/s a subset. If that's so, I guess a SATA drive can be treated as a (less sophisticated) SAS drive.
That is very interesting, so any compliant SAS controller will also be able to talk SATA. I assume the opposite is not true? ie. That a SAS disk can talk SATA? It would actually make my job easier if I could use a SATA controller to talk to a SAS drive, but that seems unlikely? FYI: I do a lot of forensic imaging. Basically removing drives from random computers, hooking them up to mine and doing a dd capture of the full drive. Have not dealt with a SAS drive yet. Greg -- Greg Freemyer The Norcross Group Forensics for the 21st Century -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org
Greg Freemyer wrote:
On 3/6/07, Russell Jones
wrote:
I assume the opposite is not true? ie. That a SAS disk can talk SATA?
I'd think not. But IDK.
It would actually make my job easier if I could use a SATA controller to talk to a SAS drive, but that seems unlikely? Try googling for the standards body that draws up the SAS standard. You may find some official info or forums there. Maybe do a site:xyz.org search on the SATA standards body for SAS. FYI: I do a lot of forensic imaging. Basically removing drives from random computers, hooking them up to mine and doing a dd capture of the full drive. Have not dealt with a SAS drive yet.
Maybe you should get an SAS controller? I don't know. We do have a server fitted with SATA drives providing a SCSI hardware RAID-5 array. It's probably of this type as it comes in two configurations, SAS and SATA. I assumed they were different cards, but perhaps not. -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org
participants (3)
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Anders Norrbring
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Greg Freemyer
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Russell Jones