Software RAID 1 + RAID 0 on the same partitions

Posted on 2011-05-03
Last Modified: 2012-05-11

I have Windows 2008 R2 machine with 2 physical HDD's.
It will work with SQL 2008

Currently there is software mirroring RAID 1 configured on 2 HDD's 1 single partition on both.

I was wondering it it makes sense to create 2 partitions:
1) RAID 1 for data
2) RAID 0 for temp / swap etc

Does it make sens when everything is still on 2 single HDD's?

Maybe also leave 2'nd partition without any software RAID?

Does anyone has experience with such scenarios?
Question by:kheim2008
    LVL 8

    Accepted Solution

    Since you have 2 HDD, the safest way to keep your server up and running is RAID1. If you mix the software RAID with 0+1 (unlikely) again 2 HDD's overall performans will go down especially in busy times. If I were you I would not jeopardize SQL server with that gambling. I think that server also you DC, am I right? If so, just make it RAID 1. Might be slow but will be safe.
    LVL 11

    Expert Comment

    Only one RAID is enough, because you use software RAID, partitioning drive have no use, only cosmetic, because if you reinstall OS, you lose everything
    LVL 55

    Assisted Solution

    It makes some sense having the tempdb, swap (and logs) on RAID 0 and the OS and data on RAID 1 in that if you lose a disk you don't lose any data although SQL stops of course if you lose one of the disks and you can't do no-loss restores. Alternatively you could use RAID 1 for data and OS and then seperate non-RAIDed partitions on the remaining space, for example D: on one disk for logs, E: on the other for tempDB.

    I'd rather do the whole thing under hardware RAID 1 but that's probably not an option and it's presumably not supposed to be a high performance highly available system anyway.

    Author Comment

    so what about option: 2 physical HDD's

    Partition 1 (Software RAID 1 on HDD1 & HDD2) - system & SQL data
    Partition 2 (NonRaid on HDD1) - temp db
    Partition 3 (NonRaid on HDD2) - logs
    LVL 55

    Expert Comment

    That'd be fine, if you lose one disk you've still got the OS and data on the other and it's easy enough to create new tempDB and logs folders.

    Author Comment

    Thanks, and how about performance?
    Will it be better than single RAID 1 from these 2 HDD's?
    I don't wish do compromise safety if no or marginal performance can be obtained.
    LVL 8

    Expert Comment

    RAID 0 will give you better performance (almost twice) but if something happens only 1 HDD you loose everything inlcuding second HDD. Because data shared and written on 2 HDD simultaneously. RAID1 speed will be equal to 1 HDD's performance but same data wll be written on 2 HDD twice. With RAID1 if you loose 1 HDD your system and data still be available and safe.

    Author Comment

    I understand the risks (I know RAID logic)
    I guess my question is more about fact of software RAID on same HDD's

    Again (I'm looking at software raid configured as below)

    [C:    ] [D:    ]
    HDD1 [RAID 1] [RAID 0]
    HDD2 [RAID 1] [RAID 0]
    compared to what I have now:
         [C:             ]
    HDD1 [RAID 1         ]
    HDD2 [RAID 1         ]

    Open in new window

    LVL 30

    Expert Comment

    i use 4 drives in a raid 10 for performance and protection(a raid 1 array of raid 0 arrays)  as 2 drives can fail as long as they are in different sides of the raid array

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