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SSD Cache or OS drive?

Hello everyone,

I'm planning a new build and I'm in doubt. I'll buy a 256 GB Samsung 840 Pro and 2 WD Black 3TB drives for a RAID 1. What's the best choice: have the SSD act as a cache for the RAID or making it my OS drive? My planned usage is virtualization, development entertainment center of sorts and a lot of gaming.

Thanks in advance for the help,

Léster

P.D.: AFAIK Asus mobos don't have the 64 GB limitation of Intel's SRT so I can fully devote the SSD to caching.
13 answers Last reply Best Answer
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  1. Make the SSD your OS drive.

    The OS is the most frequently referenced data no matter what activity you're performing. You want the data accessed most to be accessed the quickest. This will help with virtual disk speeds (paging) as well.

    With that disk size, I'd also put my most frequently used apps on it as well.

    If you want to utilize SSD caching, pick up a 40GB or 64GB. Even used or refurbed is fine since it's just acting as cache.
  2. I don't know how Asus would get around intel's 64gb cache size limitation, but assuming you can, there is no best choice here, there is only personal preference.

    I'm Running 3 3tb drives in raid 5. I still personally prefer to have my os/programs on a separate physical drive than my data, rather than just a separate partition. However, all my game & programs fit within the 240gb SSD space I have, YMMV.
  3. quilciri said:
    I don't know how Asus would get around intel's 64gb cache size limitation


    Here's a reference to the removal of the 64 GB limitation in Asus mobos:
    http://www.hardwarecanucks.com/forum/hardware-canucks-reviews/50312-asus-sabertooth-x79-motherboard-review-15.html

    Quote:
    Next, boot into Windows, open AI Suite and go to ASUS SSD Caching under the Tools menu. You should see a screen similar to the one above. We should mention here that there are no capacity limitations for the SSD as there are with Z68 (64GB) so our 128GB M4 worked without a partition. The benefit of this is a higher limit on the amount of programs that can be cached on the SSD.


    quilciri said:
    assuming you can, there is no best choice here, there is only personal preference.


    Somehow I'm under the impression that having the SSD as a cache allows me to enjoy the fast transfer speeds of the SSD and the enormous storage of traditional HDDs. Also, AFAIK SSDs have a smaller number of writes than HDDs so I'd avoid writing sensible data on them. Though I don't know if I'm right on this.
  4. There are only two connections on the Marvell controller. I think the answer to your question is in the second image of the hardwarecanucks review.

    You can run SSD caching for a single HDD by plugging it and an SSD into the two Marvell SATA connections.
  5. Best answer
    Given you are using the Sabertooth X79 as was in your linked example, you have three separate disk controllers:

    1) Intel SATA III with 2 connections.
    2) Intel SATA II with 4 connections.
    3) Marvell SATA III with 2 connections.

    Given the disks you have available:

    I'd set up my SSD on the Intel SATA III controller in SATA6G_1. I'd install the OS on this disk.

    I'd set up my RAID 1 config with the two HDDs on the SATA II controller (since neither disk will utilize the full SATA II bandwidth allocated to each connection) on SATA3G_3 and _4. I'd attach my DVD player to the SATA II SATA3G_6. Build the RAID 1 array, of course, with disks on 3 and 4.

    The Marvell SATA III controller will be open for use. For the heck of it, I'd set it up and configure the Marvell controller for RAID, but it will just run in AHCI mode if no array is built. You can't take advantage of the Asus Caching with RAID 1 because it will only work with an HDD/SSD plugged into the two available Marvell controllers SATA connections. If there were three connections off the Marvell controller, that might be a different story, but I'm not sure the caching can work with an SSD across two HDDs either.

    At any rate, your RAID 1 array should give you read speeds near double a single disk. This will cut load times down between maps/scenes in games significantly.
  6. A very detailed, thorough answer. Thank you.
  7. lbelloq said:

    Somehow I'm under the impression that having the SSD as a cache allows me to enjoy the fast transfer speeds of the SSD and the enormous storage of traditional HDDs. Also, AFAIK SSDs have a smaller number of writes than HDDs so I'd avoid writing sensible data on them. Though I don't know if I'm right on this.


    SSD's technically have fewer write cycles than HDD's, but for a consumer PC, it doesn't matter. Even the TLC ssd's (which have the shortest lifespan of all the ssd's) can have 40gb written to it every day for 10 years before the NAND begins to fail.
  8. ubercake said:

    At any rate, your RAID 1 array should give you read speeds near double a single disk. This will cut load times down between maps/scenes in games significantly.


    Most onboard raid controllers afaik don't support reading from a different place on each drive at once in a mirrored array.

    Are you thinking of raid 0, or have onboard raid controllers made greater strides than I thought?
  9. lbelloq said:


    Very nice. That does remind me of something I forgot to mention as well - if you are at all worried about write performance, caching is not the way to go.
  10. quilciri said:
    ubercake said:

    At any rate, your RAID 1 array should give you read speeds near double a single disk. This will cut load times down between maps/scenes in games significantly.


    Most onboard raid controllers afaik don't support reading from a different place on each drive at once in a mirrored array.

    Are you thinking of raid 0, or have onboard raid controllers made greater strides than I thought?


    Here are some RAID 1 basics:
    http://en.wikipedia.org/wiki/Raid_1#RAID_1

    Older controllers don't provide the advantage of reads from more than one disk in the array. Maybe that's what you were thinking?
  11. Your wiki link says that most RAID 1 implementations do not read from multiple drives at once (at least not in any way that increases performance), which is what I was trying to say.

    Quote:
    That is, a RAID 1 array of two drives can be reading in two different places at the same time, though most implementations of RAID 1 do not do this


    My thinking is that the ones that are able to read from both drives are newer discrete controller cards, not onboard RAID.
  12. quilciri said:
    Your wiki link says that most RAID 1 implementations do not read from multiple drives at once (at least not in any way that increases performance), which is what I was trying to say.

    Quote:
    That is, a RAID 1 array of two drives can be reading in two different places at the same time, though most implementations of RAID 1 do not do this


    My thinking is that the ones that are able to read from both drives are newer discrete controller cards, not onboard RAID.


    Funny though. That part of the entry is among the only that say 'citation needed'.

    That usually appears for entries that have just been added.

    Here's a little tidbit about the X79 chipsets Intel RAID controllers:
    http://wishmesh.com/2013/02/raid-1-mirror-read-speed-as-fast-as-raid-0-stripe/

    Not being able to read both disks simultaneously is probably common on mainstream chipsets and boards. Enthusiast boards and chipsets definitely offer a little more all the way around.
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