Talk:Serial Attached SCSI

message: Q: It would be interesting to see even a short list of points about how SAS compares to SATA - what limitations each one has the the other doesn't?
A: As noted in the article, SATA is limited to direct-attached connection of ATA drives only and does not support SAS drives.  SAS supports SATA drives (in fact, it uses the same internal narrow cables), a complex topology, a SCSI command set, and for SAS-native drives, a globally unique drive identifier. 70.162.144.181 02:46, 6 October 2006 (UTC)
thread_title: Q + A

message: Since parallel SCSI also support hot swap. I've remove the following line 
* SAS supports hot swapping.
--Sltan 05:48, 23 January 2007 (UTC)
thread_title:  SAS vs parallel SCSI 

message: There are references for this article but they do not follow Wikipedia's guideline for citing sources at WP:CITE. Ceros 04:15, 5 December 2006 (UTC)
thread_title: Cleanup

message: In the article about SATA it can be read that SATA II shouldn't be confused with SATA/300. Which is said on www.sata-io.org (the ones who make the standard).
So the comparsion between SATA and SAS maybe should be changed. Like NCQ is an "additional capability" as they say, nothing about that it should be in SATA/300.
Aqualize 22:55, 5 February 2007 (UTC)
thread_title:  SATA 1 and SATA 2? 

message: A Hershey's kiss for size comparison?
:but they "are one of the most popular candies in the world". Yep, never heard of those before :)
Any chance someone could make a new photo and include a ruler in the picture to show the size/scale?  One with metric and imperial would be nice :)  It would be a little more useful than using a chocolate as the reference object.  —Preceding unsigned comment added by 134.7.248.130 (talk) 05:18, 20 November 2007 (UTC)
thread_title:  Photo 

message: List of SAS & SAS RAID controllers - in fact it is a commercial ad with prices, "buy" button etc., not a list. Is it ok in wikipedia.org?  —Preceding unsigned comment added by 80.75.94.163 (talk) 12:33, 25 November 2007 (UTC)
thread_title:  is it ok? 

message: "SATA devices are uniquely identified by their port number connected to the Host bus adapter while SAS devices are uniquely identified by their World Wide Name (WWN)."
so how are SATA drives within a SAS system identified? Plugwash (talk) 18:18, 12 April 2008 (UTC)
thread_title:  drive identification 

message: In the frame definition layer, I think "SPP transport layer" is a typo; it should be "SSP transport layer".  At least I can't find a reasonable definition for SPP, whereas SSP is "Serial SCSI Protocol" :-).
--klode (talk) 16:20, 20 May 2008 (UTC)
thread_title:  error in SAS layers diagram? 

message: I'd like to know what the common usage for SAS drives would be (mission-critical servers, mid-range servers, low-demand servers, etc.) I'd also like to see some numbers as to how many are out there, how many will be out there, etc. Will this technology eventually dominate all server applications? ---Ransom (--208.25.0.2 (talk) 15:56, 3 June 2008 (UTC)
replies: text: Please read WP:FORUM, but the short answer is that SAS already has taken over all of the above. -- KelleyCook (talk) 16:22, 3 June 2008 (UTC)
replies: text: Could you please cite a reference?  It seems to me that, if anything, SATA has taken over all but very high-end servers. Quanstro (talk) 20:27, 19 December 2008 (UTC)
thread_title:  Usage / deployment? 

message: Is SAS compatible with SATA 6.0 Gbit/s? Urvabara (talk) 14:56, 27 August 2008 (UTC)
thread_title:  Is it compatible with SATA 6.0 Gbit/s? 

message: In the first paragraph...
"At present it is slightly slower than the final parallel SCSI implementation, but in 2009 it will double its present speed to 6 Gbit/s"
I don't think you undestand...it's 3 Gb/sec PER LANE...most SAS HBAs have 2 ports, 4 lanes per port (8 total) -- That's 2400 MB/sec half duplex, 4800 MB/sec full duplex...
Compare that to a Parallel SCSI HBA which has two independent U320 Parallel SCSI Busses (Not full duplex)...640 MB / sec.
I don't see how anyone can say it is slower under any circumstance.  208.69.85.39 (talk) 21:15, 8 December 2008 (UTC)
thread_title:  Slower than Parallel SCSI? 

message: Within the SAS domain section it is stated that a SAS domain can have up to 16,256 devices, while under the comparison to parallel scsi it is stated that sas supports up to 16,384 devices (the latter being 2^14, and thus sounding more correct to me, though I don't know). Are these numbers correct? If so it might be clearer if a note stating this were added. Peter Law (talk) 17:45, 13 January 2009 (UTC)
thread_title:  Number of devices 

message: The article compares sas, scsi and FC port identifiers. It states that the "port identifier" in FC is the WWPN. This seems slightly confusing as the word "Port-ID" is usually referring to the identifier assigned in a fabric or loop to communicate with the port. The WWPN is not used for the communication itself. I think the comparison is fair as long as the "port identifier" is removed. Instead one could say something like HW address..  — Preceding unsigned comment added by Qualle14 (talk • contribs) 22:53, 14 March 2012 (UTC)
thread_title:  port identifiers 

message: SAS is reinventing the wheel. All the perks praised in this article were available 20 years ago in IBM's Serial Storage Architecture (SSA): 
* point-to-point links
* loop topology
* dual-ported drives
* simultaneous multi-link transfers
* multiple initiators (up to 2 in RAID and up to 8 in JBOD configurations)
* "target mode SSA" communication between initiators
It even had optical extenders which allowed to extend the SSA loop between datacentres at distances up to 10 km.
The only difference being the electronic circuitry at the time was capable of 20 MB/s per link, upgraded in late 90s to 40 MB/s per link. 15 years later the only improvement is frequency increase mere 15-fold. SSA adapters allowed port 1 on adapter A to participate in a loop with port 2 on adapter B with the remaining two ports not sharing a loop. SAS adapters I've seen so far demand port 1 to be joined with port 1 which makes the implementation more error prone.
It seems the WP article on SSA is written by a newbie who knows nothing about it.  — Preceding unsigned comment added by 82.152.33.232 (talk) 22:20, 4 January 2014 (UTC)
thread_title:  SAS vs. SSA 

message: I believe the SFF-8470 connector has 34 pins, not 32. I have already changed the article.
Unfortunately, I couldn't find this clearly mentioned in the SFF-8470 standard. It references figure 9, but the references to this figure in the PDF are not links or they do not work. And the figure 9 seems to describe a particular connector variant, not the pin numbering as referenced. But the values (m and n) in the tables correspond as do other verification methods I tried (none of them significantly authoritative though).
The pin counts should be as follows:
* 16 signal pins,
* 18 ground pins.
The ground pins are actually 9 dual-sided pairs and could therefore be counted as two per pair, giving 18 pins altogether. Together with the signal pins we get the total count of 34 pins. This is also close to the original number of 32, so the original author might have used the same counting method.
Anyone knowing better is welcome to correct me (and, if possible, leave an explanation comment here). :-)  — Preceding unsigned comment added by JITR (talk • contribs) 09:01, 8 October 2015 (UTC)
thread_title:  SFF-8470 connector pin count 

message: missing section MULTILINK   (Serial Attached SCSI#MULTILINK) --Tpyvvikky (talk) 13:21, 13 June 2020 (UTC)
thread_title:  [[MultiLink SAS]] 

message: > However, because SCSI commands that can do that are rare, and an SAS link must be dedicated to an individual command at a time, this is generally not an advantage.[10]
The link [10] is to a Tom's hardware piece (authoritative?), and doesn't address the point made that SCSI commands that are duplex are rare.
:That statement is from a very non-enterprise POV. As soon as you add expanders, full duplex becomes vital. I'd say we remove it. --Zac67 (talk) 11:14, 22 December 2020 (UTC)
thread_title:  [[ Duplex ]] 

message: In the "Comparison with parallel SCSI" section it says
"SAS allows a higher transfer speed (3, 6 or 12 Gbit/s) than most parallel SCSI standards. SAS achieves these speeds on each initiator-target connection, hence getting higher throughput, whereas parallel SCSI shares the speed across the entire multidrop bus."
I'm guessing that the "initiator" is the disk controller and the target is a set of drives with it's own SAS connector to the disk controller.   But generic words used to reference something specific in a standard, shouldn't be used without reference. BenjaminGSlade (talk) 13:03, 4 October 2022 (UTC)
replies: text: Please see the #Introduction section for initiator and target. --Zac67 (talk) 14:31, 4 October 2022 (UTC)
thread_title:  What is a "initiator-target connection" 

message: The description for SFF-8680 says "same pinout with SFF-8480" - but SFF-8480 is not in the table of connectors and there is no further elaboration. This seems like a mistake, as the real SFF-8480 is titled "HSSDB9 (High Speed Serial DB9) Connections" and has nothing to do with SAS. Perhaps it's supposed to read "same pinout with SFF-8482"? That's the only thing that would make sense in context. Mattventura (talk) 01:47, 26 June 2023 (UTC)
replies: text: That's really a typo and must be SFF-8482 as you've suspected – corrected. --Zac67 (talk) 04:57, 26 June 2023 (UTC)
thread_title:  What is SFF-8480?