Sas 2 speed

Sas 2 speed DEFAULT

Deciding between SATA vs SAS is important when considering the right storage infrastructure for such key projects as server virtualization for small business.  SATA or Serial ATA stands for Serial Advanced Technology Attachment and is the next generation computer bus interface from the parallel interface ATA.  SAS, or Serial Attached SCSI, is a faster and historically more expensive interface.

sata vs sas

Because SAS drives are able to rotate so much faster (up to 15K RPM) than SATA drives (typically K RPM), seek times may be substantially faster by more than 2 times.  The figure above shows different capacities and list prices of SAS and SATA drives available for a particular flavor of HP DL G7.  While SATA is the least expensive drive available, for servers, it is typically much better to go with SAS for low capacity use cases.  For example, a 10K GB SAS drive is not much more expensive than the substantially slower GB K SATA drive.

At higher capacities, high performance SAS drives climb in price steeply.  It may be better to take advantage of dedicated storage infrastructure such as Network Attached Storage (NAS) or a Storage Area Network (SAN), rather than populate a server with expensive direct attached storage.

As discussed in an almost identically titled blog entry - SAS vs SATA – what’s the difference? - SATA drives tend to be better solutions for desktops and SAS drives for servers. 

Key takeaways:

  • The performance benefits of SAS far outweigh the price difference at low capacities
  • There is a point of diminishing returns for the performance of SAS at high capacities
  • SATA tends to be a better solution for desktops and SAS for servers
  • Consider a dedicated storage infrastructure for high capacity needs

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Sours: https://www.turbotekcomputer.com/resources/small-business-it-blog/bid//sata-vs-sas-what-is-the-difference

In most cases, no. MiniSAS cables are multi-lane. Depending on the cable, controller and expander being used, each cable supports four lanes of 12G or 6G or 3G. That yields you 12G x 4 lanes = MB/s, or 6G x 4 lanes = MB/s, etc. Since standard hard drives' max transfer speed is maybe around MB/s, it will take many of those drives to saturate the bandwidth of a single cable. SSDs on the other hand are much faster, and it takes fewer SSDs to use up the bandwidth of a single cable. In some cases running two cables from your expander enclosure to your controller card will give you more speed.

Variables to be aware of when trying to get maximum speed from your SAS expander setup:

  • Use a PCIe controller card in a PCIe slot.
  • Make sure the x8 or x16 slot is an x8 signal slot. Some x8 slots are only x4 signal, thus cutting your bandwidth in half.
  • When using a 12G controller card, using a 12G expander chassis is ideal.
  • SSDs yield outrageous speed vs hard drives. Use SSDs if max speed is what you need.
  • Use SAS hard drives instead of SATA. rpm SAS drives have been found to be around 10% faster than equivalent SATA drives, at a very minor cost difference.
  • Use two hd minisas cables for optimal performance. Some expanders and controllers don't yield better performance with two cables. Some do. You'll want to try two cables to see.
Sours: http://www.sasexpanders.com/faq/
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Dell R1RNV Mini SAS cable set

Dell Part #/MPN: R1RNV


Interface Types: SAS Serial Attached SCSI

Electrical Interface: SAS-2 Serial Attached SCSI v2 - Gbps

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External SAS Cable 1m / 3ft SFF

Infiniband Part #/MPN: CAB-SAS-EXTM-BN-OE


Interface Types: SAS Serial Attached SCSI, SFF

Length: 1m / 3ft

Electrical Interface: SAS-2 Serial Attached SCSI v2 - Gbps

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Dell JD Internal SAS Cable

Dell Part #/MPN: DELJD-BN-OE


Interface Types: SAS Serial Attached SCSI, SATA, SFF, SFF

Length: m / 20"

Electrical Interface: SAS-2 Serial Attached SCSI v2 - Gbps

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Sours: https://www.disctech.com/adapters-cables/storage-cables/sata-sas-cables-adapters/interface-speed/SASSerial-Attached-SCSI-vGbps

SAS vs. SATA

Speed

Throughput is the amount of data that can be moved, processed, or read and written in a certain amount of time. To measure drive speeds, drive throughput is benchmarked, or tested. (IOPS may also be measured; throughput and IOPS results often suggest the same things about a drive.) The throughput of SAS drives is usually higher than that of SATA drives; there are simply fewer delays in general. However, there is some overlap between slower SAS drives and faster SATA drives.

The number of revolutions per minute (rpm) that a drive can perform affects throughput. Several factors affect drive speed on the whole, but generally the higher the rpm, the faster the drive's throughput and similar performance functions will be. Most consumer-level SATA-based drives operate at rpm and up to rpm, while most SAS-based drives operate between rpm and rpm.

This difference in speed is most noticeable when handling large files. A rpm SAS drive will most likely read and write a GB file faster than a rpm SATA drive will.

Small sample of benchmark testing data compiled by Ian Mapleson of SGI Depot (last updated Nov ). Visit the SGI Depot site for more stats.
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Small sample of benchmark testing data compiled by Ian Mapleson of SGI Depot(last updated Nov ). Visit the SGI Depot site for more stats.

The data transfer rates of hard drives are also closely related to the type of connector used, whether it is SATA or SAS. A SATA cable transfers data at a rate of about MB/s, compared to SATA-II's MB/s, and SATA-III's MB/s. SAS cables traditionally transferred data at up to MB/s; newer versions can transfer up to MB/s.

Storage Capacity

SAS prioritizes speed over storage. Accordingly, the vast majority of SAS drives that are sold have fewer than GB of hard disk space. Those with over GB of space can be very expensive. In contrast, SATA prioritizes storage, so finding an affordable SATA drive with 1TB or more of space is easy.

Reliability

A significant difference between SAS and SATA is that SAS is engineered to withstand 24/7 use in enterprises, such as datacenters. While a SATA drive could technically be used in all the same ways that a SAS drive could be (e.g., for a server), it would perform more slowly and would be more likely to fail (or suggest failure—give a false positive—even when it has not technically failed). This is a costly problem for businesses that depend on reliable hard drives. The mean time between failures (MTBF) for a SAS drive is to million hours of use at 45 °C, while the MTBF for a SATA drive is , hours to million hours of use at 25 °C.

It is possible to have a hard drive last for several years, regardless of the tasks performed on it; all performance and reliability statistics exist on a bell curve, with some drives performing better or worse than others. Brand may also matter when hunting for the most reliable drive, be it SAS or SATA. In , the backup service Backblaze analyzed the reliability of three popular hard drive brands: Hitachi, Western Digital, and Seagate. Hitachi and Western Digital were the most reliable over time, while nearly 30% of Seagate drives failed after three years of use.

Power Consumption

SAS uses more power than SATA does, which allows it to support server backplanes and have longer cables. A SAS drive uses at least two times as much signaling voltage as a SATA drive does.

Prices for SATA and SAS drives

As of January , a 1TB rpm SAS drive goes for about $ on Amazon. e.g. $97 for a 1 TB SAS drive. The SATA equivalent is about 10% cheaper at $

Prices usually increase according to the amount of storage space available. For example, the 2TB version of the same hard drive costs $ for SAS and $ for SATA.

Uses/Applications

Personal Computing

While both SATA and SAS drives can be used in personal computing, most small business offices and personal setups will not make regular use of SAS' data transfer capabilities. Sacrificing the storage space of a SATA drive, which typically has at least twice as much hard disk space as a SAS drive for a fraction of the cost, will not be a good trade-off in most all cases.

Servers

When it comes to serving up web pages on a web server or hosting games on a game server, SAS is the superior choice because of its low failure rate and high-speed data transfer capabilities.

Video Explaining Uses

The video below talks further about how SAS and SATA are used.

SATA and SATA Revisions

One point that may cause confusion is the fact that there are actually different kinds of SATA drives: SATA revision 1, SATA revision 2, and SATA revision 3 (and and ). With each revision, standards have risen, particularly when it comes to transfer speeds. A SATA drive has a potential transfer speed of MB/s compared to a SATA III's potential MB/s. As such, those who want the affordable storage capacity of a SATA drive, but also crave the speed of a SAS drive, should purchase a SATA III / SATA revision 3 drive with a high rpm.

Watch the video below to learn more about the history of SATA and how the latest versions of SATA compare with SAS.

Cables

SAS and SATA cables have two ends, one to connect to a drive and one to connect to power via the motherboard. (Hard drives also connect directly to power with a separate cable.) Because of their higher voltage, SAS cables can be up to 10m (33ft) long, while SATA cables can only extend up to a meter (3ft) in length.

A pin SATA power cable.
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A pin SATA power cable.

SAS cables vary considerably in length and purpose, but most modern SAS cables have 26 to 36 pins and are powerful enough to support multiple devices and backplanes. There are internal and external SAS cables, extension cables, and even cables that will hook SAS controllers to SATA devices.

Meanwhile, SATA's data connector has seven pins, or conductors: three grounds and four active data lines. At the opposite end of the cable, SATA's power connector is much wider and has 15 pins that supply electricity to the drive, ground the cable, and support drive spinup.

SAS is backward compatible with SATA-II and SATA-III, while SATA drives are not backward compatible with SAS.

References

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Speed sas 2

Serial Attached SCSI Standards Overview

3Gb/s SAS
(SAS-1) 6Gb/s SAS
(SAS-2) 12Gb/s SAS
(SAS-3) Logo 3Gb/s SASLogo 6Gb/s SASLogo 12Gb/s SASRaw bandwidth (Gbit/s) 3 Gb/s 6 Gb/s 12 Gb/s Raw bandwidth (Gbit/s)
Wide Port (4 Ports) 12 Gb/s 24 Gb/s 48 Gb/s Encoding 8b/10bTransfer speed (MB/s) MB/s MB/s MB/s Transfer speed (MB/s)
Wide Port (4 Ports) MB/s MB/s MB/s Discovery by initiators by SAS ExpandersSATA compatible
(operation of SATA
HDDs on SAS bus) yes Zoning vendor-specific T10 standardised Spread-Spectrum-Clocking yes Connection Multiplexing (3Gb/s in 6Gb/s) yes[1]
Sours: https://www.thomas-krenn.com/en/wiki/Serial_Attached_SCSI_Standards_Overview
BUL Armory SAS II UR - Review of Ultimate Racer USPSA/IPSC Open Gun!

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