Re: sata or sas? performance greatly increased with sas?

<markm75c@xxxxxxxxx> wrote:
So you dont think the 7200 rpm (single port)? sas drives (ES2.1) from
seagate.. ie: 500gb, would be worth the bother over 32MB enterprise
drive equivalents that are sata?

Based on the spec it's the same drive mechanism except less cache on
the SAS model, the firmare is somewhat different though. It depends on
whether you need to mix in SAS 15k disks in the same chassi/controller
or not, if not I'd save the money and go for the lower cost SATA ES.2
drives.

There CAN be differences in other areas, in this case it appears to be
that the SAS controller is faster (up to 50% faster CPU, slightly
faster memory). It can also handle more cache (4GB instead of 2GB),
though in most cases 2GB is probably enough.

The CPU/memory difference should give it higher streaming read/write,
if given enough disks (as a guess it'll may start showing up at
perhaps 10-12 disk for read and RAID1/10/5 write, 8-10 disks for RAID6
write?).

However, for most people STR has little or NO effect, it's high enough
that about the only possible exception I can think is HD video editing
using *uncompressed* video and I'm not sure even those guys would
typically notice it (probably run into CPU utilization limits even on
a dual/quad before a STR limit that high is noticeable).


I dont think we take a ton of file I/O hits now.. but our file system
is stored on the host server side.. with the new server it will be
from within a VM.

I'm leaning towards building a nice array of SAS drives on the new
server just for a VM or two that will do nothing but file sharing
(network shares)..

Or maybe use that SAS array to power say 2-3 VMS, the rest will be on
a sata array..

That's where it starts to get complicated and where there's few good
guides. It MAY work well to use both SATA and SAS disks on a
controller, and it may not! If not you do want the SAS ES.2 models for
bulk storage instead (or two different controllers but that
complicates other things).

There's a few anecdotes but not much beyond that.


With file sharing right now, on the main host, we have about 60 open
files.. but for most other sql apps that fall under our one sql vm,
i'm guessing we dont have more than a handful or maybe 15 at the most
simultaneous hits as of now, though this may grow.

Number of files isn't a particularly usefull metric for someone
outside which doesn't have knownledge of your system.

If you want to size this try to figure how much read IOPS and write
IOPS you have, then try to figure out how many of those can be
gathered via a large write-back cache (this will have a big impact if
you use RAID5 or RAID6 and 10+% writes).
.

Relevant Pages

  • Re: ????SATA or SCSI????
    ... Actually, drive failure in the first week is not surprising, whether SATA, SAS, SCSI or IDE. ... Look at the curve for failure on HDs, and you'll see it's really high initially and really high towards the EOL, and very low in the middle. ... You never considered SATA, which indicated you do not like it, and that **could** bias your opinion of the drive failure as being insignificant in a technology that you like, but it may have been perceived as a major failure if it had been SATA that you do not like. ... I haven't yet deployed a server with SATA drives and I'd rather not take a chance. ...
    (microsoft.public.windows.server.sbs)
  • Re: sata or sas? performance greatly increased with sas?
    ... whether you need to mix in SAS 15k disks inthesame chassi/controller ... ifnotI'd savethemoney and go forthelower cost SATA ES.2 ... drives would prove beneficial? ...
    (comp.arch.storage)
  • Re: HP MSA 2000 series san vs Promise or other brands out there? Thoughts?
    ... with 3 physical servers and about 20 ... requires their brand of drives and they dont offer 1TB SAS at this ... 48TB (48 drives) dual controller, ... Personally I think SATA if fine, but you should use RAID6, ...
    (comp.sys.ibm.pc.hardware.storage)
  • Re: [opensuse] SATA / SAS controllers.
    ... as it would seem to apply to all SAS ... > How does SAS compare to other serial technologies, like SATA? ... > performance SAS disk drives and high capacity low cost SATA disk ... > drives to the same SAS controller. ...
    (SuSE)
  • Re: HP MSA 2000 series san vs Promise or other brands out there? Thoughts?
    ... with 3 physical servers and about 20 ... requires their brand of drives and they dont offer 1TB SAS at this ... 48TB (48 drives) dual controller, ... Personally I think SATA if fine, but you should use RAID6, ...
    (comp.sys.ibm.pc.hardware.storage)
Loading