Drive questions

[Carlos1010]

Hi all,

So just for curiosity I have 2 questions about drives so here they are!

 

1. What is faster for storage a PCIE SSD or a RAM drive?

 

2. Is there such thing as a PCIE HDD? 

 

Thanks

[Orangeator]

1 minute ago, Carlos1010 said:

Hi all,

So just for curiosity I have 2 questions about drives so here they are!

 

1. What is faster for storage a PCIE SSD or a RAM drive?

 

2. Is there such thing as a PCIE HDD? 

 

Thanks

 

1. I believe a RAM drive but I wouldn't recommend that. Go with a PCIE SSD.

2. No there is no such thing as a PCIE HDD to my knowledge.

[NeoSk11zle]

2 minutes ago, Carlos1010 said:

Hi all,

So just for curiosity I have 2 questions about drives so here they are!

 

1. What is faster for storage a PCIE SSD or a RAM drive?

 

2. Is there such thing as a PCIE HDD? 

 

Thanks

Pci express SSD is Fast for lots of storage and a Ram Drive is ram (?)

[Guest]

Fastest (according to almighty Linus) are RAM drives

 

 

[DrM]

1. ram disk, but its barely noticable since youre still limited by filesystems and cpus

2. no, but theres pcie sata cards

[Carlos1010]

1 minute ago, DrM said:

1. ram disk, but its barely noticable since youre still limited by filesystems and cpus

2. no, but theres pcie sata cards

Pcie to sata? Isnt that a bottleneck? 

[Electronics Wizardy]

2 minutes ago, Carlos1010 said:

Pcie to sata? Isnt that a bottleneck? 

Not really. You can get 12gb/s sas and there is no drive that is faster than 400mB/s and sas can support 1.5 gB/s

[Carlos1010]

7 minutes ago, Electronics Wizardy said:

Not really. You can get 12gb/s sas and there is no drive that is faster than 400mB/s and sas can support 1.5 gB/s

Is sas=sata?

[Electronics Wizardy]

10 minutes ago, Carlos1010 said:

Is sas=sata?

not really. 

 

Its basically sata but better. Its used for enterprise drives + DAS

 

-support for longer cables

-support for splitters or expander(up to 16000 drives per port)

-12gb/s

 

[mariushm]

RAM disks are faster, but the information is stored in computer's RAM so if there's some power failure or you shut down the PC, you lose data. People using RAM drives usually also use an UPS (uninterruptable power supply) to prevent this.  Also, some RAM drives can be configured in such  a way as to copy the contents down to a regular hard drive when you shut down the PC, and reload the contents back in memory when you initialize the system.

 

There were also some devices in the past like gigabyte i-ram which allowed users to connect up to 4 memory sticks (4 GB in total) and a chip on the device made the product be seen by the computer as a SATA device: http://www.gigabyte.com/products/product-page.aspx?pid=2180#ov

These also had a battery on them and could charge with energy from the PCI slot and keep the ram retain the information folr days

 

Also it's kind of obvious, but in order for programs to work with data, the data has to be copied in memory, so eventually data stored in PCIe drives ends up in computer memory. Naturaly, this copying to memory part is an extra step that RAM disks don't have,

 

2. Is there such thing as a PCIE HDD? 

 

PCI-e HDD ... no, not really.  When you say HDD people most often think of mechanical drives with rotating platters. The top hard drives probably only achieve maximum transfers of around 300 MB/s, so they don't even reach the limits of a regular SATA port (~550 MB/s)

Some SSDs can go way over this 6gbps (~550 MB/s) limitation of SATA so it makes sense to avoid SATA and go straight to PCIe. 

 

PCI-e is made out of lanes, for a pci-e x16 has 16 lanes. On PCI-e v2.0 , each lane is capable of a maximum speed of 500 MB/s, on pci-e v3.0 each lane is capable of around 985 MB/s. So a pci-e x4 could give you 2000 MB/s if it's v2.0 or about 3950 MB/s if it's v3.0

M.2 connectors on motherboards have the contacts for up to 4 pci-e lanes AND  sata port  AND usb AND some other things (but not all may be present at same time)

There are motherboards that use pci-e v2.0 lanes to implement the connector, there are motherboards that implement pci-e v3.0 lanes (some go with 2 pci-e v3.0 lanes instead of 4 pci-e v2.0 lanes)

 

Motherboards also use sometimes additional sata controllers to offer more SATA ports on motherboards. There are cheap controller chips which create 2 SATA ports each capable of 550 MB/s but the chip itself connects to the system using just one pci-e lane, and even that sometimes it's only v2.0  - it works because rarely someone uses both sata ports at the maximum speed so the limitation is not obvious.

 

 

[Captain_WD]

4 hours ago, Carlos1010 said:

~snip~

Hi there

 

My two cents: 

- RAM disks have better performance compared to PCIe-based SSDs but have a lot of drawbacks and limitations. 

- Currently there are no PCIe-based HDDs as they can't even saturate SATAII and SATAIII speeds so there isn't really a need for a PCIe-based HDD. As teh guys pointed out, there are expansion cards that go in the PCIe slot in order to provide you with more SATA/PATA/SCSI/SAS ports for HDDs (in case you want more drives on your motherboard than it supports or would like to have a separate controller for purposes such as RAID.

 

What do you have in mind? What type of usage and workload are you planning?

 

Let me know if you need any help!

 

Captain_WD.