SAS storage

At work we are looking to build a SAS storage system... Now I have the cards all figured out (man there isnt much info about) and I look like getting 2 8 channel cards for 16 HDD.

The main question is;

You can use SATA HDD on SAS cards, but does this mean that the SATA HDD can run at full duplex when combined with a SAS card? I know SAS card to SAS HDD can do that fine. SO basically can a SATA HDD handle full duplex?

Cheers

[Geodude]

Originally Posted by ThEGr33k

At work we are looking to build a SAS storage system... Now I have the cards all figured out (man there isnt much info about) and I look like getting 2 8 channel cards for 16 HDD.

The main question is;

You can use SATA HDD on SAS cards, but does this mean that the SATA HDD can run at full duplex when combined with a SAS card? I know SAS card to SAS HDD can do that fine. SO basically can a SATA HDD handle full duplex?

Cheers

Wish i was clever enough to know what any of this means

Can HDD's ever be full duplex? Surely they either read or write.
I would like to know how fast this thing moves data when you get it finished!!

[appollo1]

Originally Posted by Geodude

Wish i was clever enough to know what any of this means

phew.....i thought i was the only one that was reading this mysterious code and couldn't work it out!!

Me too...

Obviously they cant physically do read and write but I think the full duplex helps with data requests etc. We arnt sure what we are going to do yet... Weather 20 500GB 7200rpm SAS discs or something a little smaller but faster RPM...

We have a 16tb SAS and its running dual fibre lines to our other boxes.

So 2gb data transit.

That's awesome!

[TSM]

Originally Posted by ThEGr33k

At work we are looking to build a SAS storage system... Now I have the cards all figured out (man there isnt much info about) and I look like getting 2 8 channel cards for 16 HDD.

The main question is;

You can use SATA HDD on SAS cards, but does this mean that the SATA HDD can run at full duplex when combined with a SAS card? I know SAS card to SAS HDD can do that fine. SO basically can a SATA HDD handle full duplex?

Cheers

what are you storage requirements? ive been looking at these things for some time so know a fair bit

There are new cards that you can put full SATA disks in then a single SSD drive to accelerate the reads, all depends on your workload. LSI Cachecade and Adaptec MaxIQ are these type of systems.

Well we currently have a 10 driver SATA Raid 5 and we seem to be getting long access Ques... What we want is high capacity if possible with more speed... Would 7200rpm SAS disks be any faster than 7200rpm SATA discs? Id have thought 10k or even 15k discs are needed to speed I/O which is a potential bottle neck atm?

Other problem is we are trying to keep cost down, pretty hard with storage we are finding, which is why SSD's arnt high on the list, that and stone think that they arnt so good, though im not sure where they are getting that from?



Or alternativley, is there any way to get rid of the access ques with the kit we have? We are using a mobo with 10 SATA build in, would it be better for example to just put some SAS cards in that system? Would that eliviate the bottlekneck?

[TSM]

Originally Posted by ThEGr33k

Well we currently have a 10 driver SATA Raid 5 and we seem to be getting long access Ques... What we want is high capacity if possible with more speed... Would 7200rpm SAS disks be any faster than 7200rpm SATA discs? Id have thought 10k or even 15k discs are needed to speed I/O which is a potential bottle neck atm?

Other problem is we are trying to keep cost down, pretty hard with storage we are finding, which is why SSD's arnt high on the list, that and stone think that they arnt so good, though im not sure where they are getting that from?

Or alternativley, is there any way to get rid of the access ques with the kit we have? We are using a mobo with 10 SATA build in, would it be better for example to just put some SAS cards in that system? Would that eliviate the bottlekneck?

SAS vs SATA at 7200 has hardly any diffrence in it and under some tests has shown to be slightly slower.
Going for 10k vs 7.2k depends a little on the workload itself, also applys to if you go for 3.5" vs 2.5" as the smaller ones have a lower access time than their larger counterparts but come at a cost.
Are you mainly looking at reads or writes on your system, what raid card are you currently using, what is the dataset like, large file reads or lots of small reads etc..
I would not go for SSDs on main storage filers but my angle was the SSD drive on the cards i listed is a read acclerator (ie 64gb of RAID cache), if it breaks then you dont loose anything apart from speed as the data is still all on the disks until you change the drive.

Look at RAID 6 instead of RAID 5 when working with large SATA/SAS filers as the rebuild time will be realy long and you could have a second disk fail while the rebuild is happening, it means more disks but it will save your nuts in the long run also you will probably need your filer to be larger because you will need again more disks to eak out the IOs.

I use the WD RE4-GP disks, they are only 5.4k but they are faster than my 3yr old Seagate ES.2 7.2k disks, there are the RE4 disks which are even cheeper but come with nearly a 25% price hike each.

You would be surprised how much the speed actualy has to do with the raid card itself, a better card may work out well but note you cant transition from one card to another, somtimes if you stay with the same make you can, i have HP cards and you can go up/down the range as long as each card supports the config you had before.