FAQ
Hello,

Does anyone have experience using a 3ware 9650SE series raid controller on
CentOS 6.0?

I am getting very sporadic throughput with moderately sized files (0.5-2GB)
on ext3. I have tried most of the mount time tuning options:

* noatime
* trying different journal types
* setting commit0 - helped a little

Even after these optimizations it doesn't seem like the raid array is
working as it should. After a few 1GB writes (dd from /dev/zero to the
raid) kjournald runs for an hour and later writes are really slow. Not only
that, using tw_cli is very slow ... whereas tw_cli is superfast if kjournald
is not churning away.

So it goes something like this

* write one 1GB file (486 MB/s)
* writes another (223 MB/s)
* any writes before the 120s commit kicks in, is ~200MB/s
* commit kicks in and kjournald starts churning
* writes are all over the map - 6-85MB/s

Maybe this is just the way it is, but it did not seem to be the case this
same hardware was running Fedora (Core) 9 and I have a similar machine where
this does not seem to be the case (I can't experiment on it at the moment).

The one thing I do not know, since I did not create the RAID or ext3
filesystem is whether the stride and stripe-width were properly selected to
match the 64k chunk size of the raid array. I don't know how to tell from
tune2fs ... output below ... its either not there or by another name.

Any help or suggestions are appreciated.

Austin

Useful Information
=============
============== /proc/mounts ====================
/dev/sda1 /tonga_raid ext3
rw,noatime,errors=continue,nouser_xattr,noacl,commit0,barrier=1,data=ordered
0 0


========= tw_cli /c2 show diag ====================
### Time Stamp: 12:34:18 01-Sep-2011
### Host Name: tonga
### Host Architecture: x86_64 (64 bit)
### OS Version: Linux 2.6.32-71.29.1.el6.x86_64
### Model: 9650SE-8LPML
### Serial #: L326025A8221043
### Controller ID: 2
### CLI Version: 2.00.11.016
### API Version: 2.08.00.017
### Driver Version: 2.26.02.014RH
### Firmware Version: FE9X 3.08.00.016
### BIOS Version: BE9X 3.08.00.004
### Available Memory: 224MB

=========================================================================Diagnostic Information on Controller //.../c2/...
--------------------------------------------------------------------------
Event Trigger and Log Information:
Triggered Event(s) ctlreset (controller soft reset)
fwassert (firmware assert)
driveerr (drive error)
Diagnostic log save mode = -
Parameter table does not exist


========== tune2fs -l /dev/sda1 ================tune2fs 1.41.12 (17-May-2010)
Filesystem volume name: /data
Last mounted on: <not available>
Filesystem UUID: 3c5f6dbb-d5dc-4f85-bc70-9b761c89c86e
Filesystem magic number: 0xEF53
Filesystem revision #: 1 (dynamic)
Filesystem features: has_journal ext_attr resize_inode dir_index
filetype needs_recovery sparse_super large_file
Filesystem flags: signed_directory_hash
Default mount options: user_xattr acl
Filesystem state: clean
Errors behavior: Continue
Filesystem OS type: Linux
Inode count: 427245568
Block count: 1708965879
Reserved block count: 85448293
Free blocks: 809305423
Free inodes: 426287552
First block: 0
Block size: 4096
Fragment size: 4096
Reserved GDT blocks: 616
Blocks per group: 32768
Fragments per group: 32768
Inodes per group: 8192
Inode blocks per group: 512
Filesystem created: Tue Sep 9 09:57:44 2008
Last mount time: Thu Sep 1 12:40:01 2011
Last write time: Thu Sep 1 12:40:01 2011
Mount count: 11
Maximum mount count: -1
Last checked: Tue Aug 30 23:12:49 2011
Check interval: 0 (<none>)
Reserved blocks uid: 0 (user root)
Reserved blocks gid: 0 (group root)
First inode: 11
Inode size: 256
Journal inode: 8
Default directory hash: tea
Directory Hash Seed: 0b324311-93a9-4c23-bf15-40965792029b
Journal backup: inode blocks
==========================================================

=================== tw_cli info c2 ===========================
Unit UnitType Status %RCmpl %V/I/M Stripe Size(GB) Cache
AVrfy
------------------------------------------------------------------------------
u0 RAID-5 OK - - 64K 6519.19 OFF OFF


Port Status Unit Size Blocks Serial
---------------------------------------------------------------
p0 OK u0 931.51 GB 1953525168 WD-WCASJ1631953

p1 OK u0 931.51 GB 1953525168 WD-WCASJ1622428

p2 OK u0 931.51 GB 1953525168 WD-WCASJ1639721

p3 OK u0 931.51 GB 1953525168 WD-WCASJ1636054

p4 OK u0 931.51 GB 1953525168 WD-WCASJ1621694

p5 OK u0 931.51 GB 1953525168 WD-WCASJ1636292

p6 OK u0 931.51 GB 1953525168 WD-WCASJ1637586

p7 OK u0 931.51 GB 1953525168 WD-WCASJ1637516

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  • Marcelo Beckmann at Sep 1, 2011 at 5:05 pm

    Em 01-09-2011 17:41, Austin Godber escreveu:
    =================== tw_cli info c2 ============================

    Unit UnitType Status %RCmpl %V/I/M Stripe Size(GB) Cache
    AVrfy
    ------------------------------------------------------------------------------
    u0 RAID-5 OK - - 64K 6519.19 OFF
    OFF
    I have the same controller on Centos 5.

    Did you try to active Cache on 3ware?

    [17:56:04 root at backup ~]# lspci | grep 3ware
    01:00.0 RAID bus controller: 3ware Inc 9650SE SATA-II RAID PCIe (rev 01)
    [17:56:11 root at backup ~]# tw_cli /c4 show

    Unit UnitType Status %RCmpl %V/I/M Stripe Size(GB) Cache
    AVrfy
    ------------------------------------------------------------------------------
    u0 RAID-5 OK - - 64K 5587.9 RiW
    ON


    In the past I had a scenario where I started with Cache OFF and had a
    poor performance, specially for write. After set Cache RiW I got better
    performance.

    I didn't test that controller on CentOS 6, but is good to know if there
    is some problem, because my company sells equipment with that controller.


    Best regards,

    --
    Marcelo Beckmann
    Suporte Corporativo - suporte at webers.com.br
    Webers Tecnologia - http://www.webers.com.br
    Curitiba (PR) (41) 3094-6600
    Rio de Janeiro (RJ) (21) 4007-1207
    S?o Paulo (SP) (11) 4007-1207
  • Austin Godber at Sep 1, 2011 at 5:54 pm
    Hello Marcelo,

    Thank you for the suggestion. I had not yet tried activating the cache
    since I was unsure whether that was a good idea or not.

    Since you have experience with this card, do you have any recommendations
    for what I should expect or avoid? Have you used EXT3 with success or are
    you using XFS or something else?

    Austin
    On Thu, Sep 1, 2011 at 2:05 PM, Marcelo Beckmann wrote:
    Em 01-09-2011 17:41, Austin Godber escreveu:

    =================== tw_cli info c2 ============================

    Unit UnitType Status %RCmpl %V/I/M Stripe Size(GB) Cache
    AVrfy
    ------------------------------------------------------------------------------
    u0 RAID-5 OK - - 64K 6519.19 OFF
    OFF
    I have the same controller on Centos 5.

    Did you try to active Cache on 3ware?

    [17:56:04 root at backup ~]# lspci | grep 3ware
    01:00.0 RAID bus controller: 3ware Inc 9650SE SATA-II RAID PCIe (rev 01)
    [17:56:11 root at backup ~]# tw_cli /c4 show

    Unit UnitType Status %RCmpl %V/I/M Stripe Size(GB) Cache
    AVrfy

    ------------------------------------------------------------------------------
    u0 RAID-5 OK - - 64K 5587.9 RiW
    ON


    In the past I had a scenario where I started with Cache OFF and had a
    poor performance, specially for write. After set Cache RiW I got better
    performance.

    I didn't test that controller on CentOS 6, but is good to know if there
    is some problem, because my company sells equipment with that controller.


    Best regards,

    --
    Marcelo Beckmann
    Suporte Corporativo - suporte at webers.com.br
    Webers Tecnologia - http://www.webers.com.br
    Curitiba (PR) (41) 3094-6600
    Rio de Janeiro (RJ) (21) 4007-1207
    S?o Paulo (SP) (11) 4007-1207

    _______________________________________________
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  • Craig White at Sep 1, 2011 at 6:58 pm

    On Sep 1, 2011, at 1:41 PM, Austin Godber wrote:

    Hello,

    Does anyone have experience using a 3ware 9650SE series raid controller on CentOS 6.0?
    ----
    use RAID 10

    Unless something has changed, RAID 5 is notoriously slow on the 3Ware controllers. Whatever you do will only incrementally speed things up. If performance is desired, RAID 5 is not the way to go.

    Craig
  • Austin Godber at Sep 1, 2011 at 7:17 pm
    Hi Craig,

    Thanks for the suggestion. I would if I could. I'd also probably try
    another file system. Though the good news is, enabling the write cache on
    that array has improved things significantly. Which, in my case, was:

    tw_cli /c2/u0 set cache=on

    Now, if only I had the battery backup unit for the card.

    Thanks, everyone for their suggestions. For now I am happy with the
    situation, but I'd be interested to hear the experiences of others.

    Austin
    On Thu, Sep 1, 2011 at 3:58 PM, Craig White wrote:

    On Sep 1, 2011, at 1:41 PM, Austin Godber wrote:

    Hello,

    Does anyone have experience using a 3ware 9650SE series raid controller
    on CentOS 6.0?
    ----
    use RAID 10

    Unless something has changed, RAID 5 is notoriously slow on the 3Ware
    controllers. Whatever you do will only incrementally speed things up. If
    performance is desired, RAID 5 is not the way to go.

    Craig
    _______________________________________________
    CentOS mailing list
    CentOS at centos.org
    http://lists.centos.org/mailman/listinfo/centos
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  • Craig White at Sep 1, 2011 at 7:47 pm
    I'm surprised that you can actually turn it on without a battery. I suspect that this is not a write-through/write-back cache but be forewarned that if there's no battery, it's possible that things you thought were written to the hard drive on shutdown/restart/hang/crash might not ever be written to the hard drive(s)

    Craig
    On Sep 1, 2011, at 4:17 PM, Austin Godber wrote:

    Hi Craig,

    Thanks for the suggestion. I would if I could. I'd also probably try another file system. Though the good news is, enabling the write cache on that array has improved things significantly. Which, in my case, was:

    tw_cli /c2/u0 set cache=on

    Now, if only I had the battery backup unit for the card.

    Thanks, everyone for their suggestions. For now I am happy with the situation, but I'd be interested to hear the experiences of others.

    Austin

    On Thu, Sep 1, 2011 at 3:58 PM, Craig White wrote:
    On Sep 1, 2011, at 1:41 PM, Austin Godber wrote:

    Hello,

    Does anyone have experience using a 3ware 9650SE series raid controller on CentOS 6.0?
    ----
    use RAID 10

    Unless something has changed, RAID 5 is notoriously slow on the 3Ware controllers. Whatever you do will only incrementally speed things up. If performance is desired, RAID 5 is not the way to go.
  • Tom Bishop at Sep 1, 2011 at 7:49 pm
    Keep in mind you really only want to enable the cache if you have a
    bbc, otherwise you are risking your data since it can/will cache
    writes...just something to keep in mind.
    On 9/1/11, Austin Godber wrote:
    Hi Craig,

    Thanks for the suggestion. I would if I could. I'd also probably try
    another file system. Though the good news is, enabling the write cache on
    that array has improved things significantly. Which, in my case, was:

    tw_cli /c2/u0 set cache=on

    Now, if only I had the battery backup unit for the card.

    Thanks, everyone for their suggestions. For now I am happy with the
    situation, but I'd be interested to hear the experiences of others.

    Austin
    On Thu, Sep 1, 2011 at 3:58 PM, Craig White wrote:

    On Sep 1, 2011, at 1:41 PM, Austin Godber wrote:

    Hello,

    Does anyone have experience using a 3ware 9650SE series raid controller
    on CentOS 6.0?
    ----
    use RAID 10

    Unless something has changed, RAID 5 is notoriously slow on the 3Ware
    controllers. Whatever you do will only incrementally speed things up. If
    performance is desired, RAID 5 is not the way to go.

    Craig
    _______________________________________________
    CentOS mailing list
    CentOS at centos.org
    http://lists.centos.org/mailman/listinfo/centos
  • Austin Godber at Sep 1, 2011 at 8:43 pm
    At this point the card is pretty much useless without that cache enabled.
    Without recommendations for making writes of 256MB or larger files faster
    without this cache enabled, I will have to accept the possible data loss in
    the event of power outage. If it is only the case of data loss during a
    power outage, I will take that ... rather than failure to write at all
    during 99% of my usage.

    I will, for the sake of not being an idiot, look into buying the BBUs.

    Austin
    On Thu, Sep 1, 2011 at 4:49 PM, Tom Bishop wrote:

    Keep in mind you really only want to enable the cache if you have a
    bbc, otherwise you are risking your data since it can/will cache
    writes...just something to keep in mind.
    On 9/1/11, Austin Godber wrote:
    Hi Craig,

    Thanks for the suggestion. I would if I could. I'd also probably try
    another file system. Though the good news is, enabling the write cache on
    that array has improved things significantly. Which, in my case, was:

    tw_cli /c2/u0 set cache=on

    Now, if only I had the battery backup unit for the card.

    Thanks, everyone for their suggestions. For now I am happy with the
    situation, but I'd be interested to hear the experiences of others.

    Austin
    On Thu, Sep 1, 2011 at 3:58 PM, Craig White wrote:

    On Sep 1, 2011, at 1:41 PM, Austin Godber wrote:

    Hello,

    Does anyone have experience using a 3ware 9650SE series raid
    controller
    on CentOS 6.0?
    ----
    use RAID 10

    Unless something has changed, RAID 5 is notoriously slow on the 3Ware
    controllers. Whatever you do will only incrementally speed things up. If
    performance is desired, RAID 5 is not the way to go.

    Craig
    _______________________________________________
    CentOS mailing list
    CentOS at centos.org
    http://lists.centos.org/mailman/listinfo/centos
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    CentOS at centos.org
    http://lists.centos.org/mailman/listinfo/centos
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  • Craig White at Sep 2, 2011 at 1:51 pm
    Data loss could conceivably occur on shutdown or restart too - just saying... You are assuming that the data that doesn't get written to disk is going to be non-essential... I wish you good luck with that. I think if one doesn't want to be an idiot, one would not enable a cache that has no means to ensure that the cache is written to disk.

    I think your take away from all of this is somewhat misdirected. Not having a BBU simply means that your writes really should always be synchronous/immediate. That shouldn't really be a problem and shouldn't impose a large performance penalty.

    Your performance issue relates more to the fact that RAID 5 implementation on the 3Ware cards is rather poor and modes such as RAID 10 (RAID 0 + 1) will give you much more speed that you realize. If you also consider on the surprisingly higher rates of failure with loss of data possibility when reconstructing a missing/dead drive on a RAID 5 setup you really should be re-examining your storage strategy.

    Craig
    On Sep 1, 2011, at 5:43 PM, Austin Godber wrote:

    At this point the card is pretty much useless without that cache enabled. Without recommendations for making writes of 256MB or larger files faster without this cache enabled, I will have to accept the possible data loss in the event of power outage. If it is only the case of data loss during a power outage, I will take that ... rather than failure to write at all during 99% of my usage.

    I will, for the sake of not being an idiot, look into buying the BBUs.

    Austin

    On Thu, Sep 1, 2011 at 4:49 PM, Tom Bishop wrote:
    Keep in mind you really only want to enable the cache if you have a
    bbc, otherwise you are risking your data since it can/will cache
    writes...just something to keep in mind.
    On 9/1/11, Austin Godber wrote:
    Hi Craig,

    Thanks for the suggestion. I would if I could. I'd also probably try
    another file system. Though the good news is, enabling the write cache on
    that array has improved things significantly. Which, in my case, was:

    tw_cli /c2/u0 set cache=on

    Now, if only I had the battery backup unit for the card.

    Thanks, everyone for their suggestions. For now I am happy with the
    situation, but I'd be interested to hear the experiences of others.

    Austin
    On Thu, Sep 1, 2011 at 3:58 PM, Craig White wrote:

    On Sep 1, 2011, at 1:41 PM, Austin Godber wrote:

    Hello,

    Does anyone have experience using a 3ware 9650SE series raid controller
    on CentOS 6.0?
    ----
    use RAID 10

    Unless something has changed, RAID 5 is notoriously slow on the 3Ware
    controllers. Whatever you do will only incrementally speed things up. If
    performance is desired, RAID 5 is not the way to go.

    Craig
    _______________________________________________
    CentOS mailing list
    CentOS at centos.org
    http://lists.centos.org/mailman/listinfo/centos
    _______________________________________________
    CentOS mailing list
    CentOS at centos.org
    http://lists.centos.org/mailman/listinfo/centos

    _______________________________________________
    CentOS mailing list
    CentOS at centos.org
    http://lists.centos.org/mailman/listinfo/centos
    --
    Craig White ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ craig.white at ttiltd.com
    1.800.869.6908 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ www.ttiassessments.com

    Need help communicating between generations at work to achieve your desired success? Let us help!
  • Austin Godber at Sep 2, 2011 at 3:03 pm
    Thank you for the clarification Craig, I am re-examining my storage
    strategy, thus my email. Sadly this machine has been in service a number of
    years and already contains more data than is possible in a RAID 10
    configuration. If I had the spare space and resources I'd be thrilled to
    switch to RAID 10. That is not the case, however. Given that, I am faced
    with the choice between having the machine entirely unusable between now and
    when I can acquire a BBU or using it with the risk of data loss/corruption,
    I will chose the latter. Neither data loss nor corruption would go
    unnoticed in the period that this will be necessary.

    Does that sound entirely unreasonable?

    Austin


    On Fri, Sep 2, 2011 at 10:51 AM, Craig White wrote:

    Data loss could conceivably occur on shutdown or restart too - just
    saying... You are assuming that the data that doesn't get written to disk is
    going to be non-essential... I wish you good luck with that. I think if one
    doesn't want to be an idiot, one would not enable a cache that has no means
    to ensure that the cache is written to disk.

    I think your take away from all of this is somewhat misdirected. Not having
    a BBU simply means that your writes really should always be
    synchronous/immediate. That shouldn't really be a problem and shouldn't
    impose a large performance penalty.

    Your performance issue relates more to the fact that RAID 5 implementation
    on the 3Ware cards is rather poor and modes such as RAID 10 (RAID 0 + 1)
    will give you much more speed that you realize. If you also consider on the
    surprisingly higher rates of failure with loss of data possibility when
    reconstructing a missing/dead drive on a RAID 5 setup you really should be
    re-examining your storage strategy.

    Craig
    On Sep 1, 2011, at 5:43 PM, Austin Godber wrote:

    At this point the card is pretty much useless without that cache enabled.
    Without recommendations for making writes of 256MB or larger files faster
    without this cache enabled, I will have to accept the possible data loss in
    the event of power outage. If it is only the case of data loss during a
    power outage, I will take that ... rather than failure to write at all
    during 99% of my usage.
    I will, for the sake of not being an idiot, look into buying the BBUs.

    Austin

    On Thu, Sep 1, 2011 at 4:49 PM, Tom Bishop wrote:
    Keep in mind you really only want to enable the cache if you have a
    bbc, otherwise you are risking your data since it can/will cache
    writes...just something to keep in mind.
    On 9/1/11, Austin Godber wrote:
    Hi Craig,

    Thanks for the suggestion. I would if I could. I'd also probably try
    another file system. Though the good news is, enabling the write cache
    on
    that array has improved things significantly. Which, in my case, was:

    tw_cli /c2/u0 set cache=on

    Now, if only I had the battery backup unit for the card.

    Thanks, everyone for their suggestions. For now I am happy with the
    situation, but I'd be interested to hear the experiences of others.

    Austin
    On Thu, Sep 1, 2011 at 3:58 PM, Craig White wrote:

    On Sep 1, 2011, at 1:41 PM, Austin Godber wrote:

    Hello,

    Does anyone have experience using a 3ware 9650SE series raid
    controller
    on CentOS 6.0?
    ----
    use RAID 10

    Unless something has changed, RAID 5 is notoriously slow on the 3Ware
    controllers. Whatever you do will only incrementally speed things up.
    If
    performance is desired, RAID 5 is not the way to go.

    Craig
    _______________________________________________
    CentOS mailing list
    CentOS at centos.org
    http://lists.centos.org/mailman/listinfo/centos
    _______________________________________________
    CentOS mailing list
    CentOS at centos.org
    http://lists.centos.org/mailman/listinfo/centos

    _______________________________________________
    CentOS mailing list
    CentOS at centos.org
    http://lists.centos.org/mailman/listinfo/centos
    --
    Craig White ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    craig.white at ttiltd.com
    1.800.869.6908 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    www.ttiassessments.com

    Need help communicating between generations at work to achieve your desired
    success? Let us help!

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  • Craig White at Sep 2, 2011 at 7:10 pm

    On Fri, 2011-09-02 at 12:03 -0700, Austin Godber wrote:
    Thank you for the clarification Craig, I am re-examining my storage
    strategy, thus my email. Sadly this machine has been in service a
    number of years and already contains more data than is possible in a
    RAID 10 configuration. If I had the spare space and resources I'd be
    thrilled to switch to RAID 10. That is not the case, however. Given
    that, I am faced with the choice between having the machine entirely
    unusable between now and when I can acquire a BBU or using it with the
    risk of data loss/corruption, I will chose the latter. Neither data
    loss nor corruption would go unnoticed in the period that this will be
    necessary.


    Does that sound entirely unreasonable?
    ----
    reminds me of dialog in 'So I Married an Axe Murderer'...

    Charlie: "For example, how many people have you brutally murdered?"

    Harriet: "Brutal" is a very subjective word. What's brutal to one person
    might be reasonable to somebody else."

    I think SATA hard drives are so cheap nowadays, that it's hard to
    justify choosing RAID 5 for more yield at the cost of performance and
    reliability.

    Craig


    --
    This message has been scanned for viruses and
    dangerous content by MailScanner, and is
    believed to be clean.
  • Joseph L. Casale at Sep 2, 2011 at 8:59 pm

    I think SATA hard drives are so cheap nowadays, that it's hard to justify choosing
    RAID 5 for more yield at the cost of performance and reliability.
    Another point to consider with slower sata discs that are also large is the prolonged
    rebuild time and degraded redundancy during this rebuild, especially with r5 vs r6.

    Additionally I can confirm as I also have several lsi cards and all perform like hell in r5/6
    even with bbu.

    jlc
  • Drew at Sep 3, 2011 at 12:14 am

    Additionally I can confirm as I also have several lsi cards and all perform like hell in r5/6
    even with bbu.
    Is that the "fast as hell" or "slow as hell" kind?

    I ask because I have a couple of IBM M5015 (rebranded LSI 9260-8i)
    controllers that I run in RAID-10 and as I'm somewhat on a budget for
    disks (coming home with $1200 worth of 15k SAS drives will get me
    shot) I'd rather run a RAID-5/6 array if the performance degradation
    is minimal. And yes, mine do have the BBU. ;-)

    Not that the performance of an 8x80GB SATA-300 array is much to write
    home about in the first place, but for my purposes it works fine.


    --
    Drew

    "Nothing in life is to be feared. It is only to be understood."
    --Marie Curie
  • Craig White at Sep 3, 2011 at 5:31 am

    On Fri, 2011-09-02 at 21:14 -0700, Drew wrote:
    Additionally I can confirm as I also have several lsi cards and all perform like hell in r5/6
    even with bbu.
    Is that the "fast as hell" or "slow as hell" kind?

    I ask because I have a couple of IBM M5015 (rebranded LSI 9260-8i)
    controllers that I run in RAID-10 and as I'm somewhat on a budget for
    disks (coming home with $1200 worth of 15k SAS drives will get me
    shot) I'd rather run a RAID-5/6 array if the performance degradation
    is minimal. And yes, mine do have the BBU. ;-)

    Not that the performance of an 8x80GB SATA-300 array is much to write
    home about in the first place, but for my purposes it works fine.
    ----
    I don't know how either of us could have made our opinions any more
    clear...

    Don't use the 3ware/LSI SATA RAID controllers in RAID 5 or RAID 6 mode
    if performance and reliability are of concern. I only use hardware RAID
    because performance and reliability are my concern. I am told that the
    Areca cards are much better on RAID 5/6 but I have no first hand
    experience with them. While you may get better performance with
    write-back caching (don't enable without a BBU), the improvement is
    incremental. Stick with RAID 10.

    Craig


    --
    This message has been scanned for viruses and
    dangerous content by MailScanner, and is
    believed to be clean.
  • Drew at Sep 3, 2011 at 9:35 am

    I don't know how either of us could have made our opinions any more
    clear...
    Just curious dude. "perform like hell" could go either way.
    Don't use the 3ware/LSI SATA RAID controllers in RAID 5 or RAID 6 mode
    if performance and reliability are of concern. I only use hardware RAID
    because performance and reliability are my concern. I am told that the
    Areca cards are much better on RAID 5/6 but I have no first hand
    experience with them. While you may get better performance with
    write-back caching (don't enable without a BBU), the improvement is
    incremental. Stick with RAID 10.
    Somebody at IBM must not have gotten the memo then as the
    M5015/9260-8i is their top of the line on-board RAID controller. :-)

    --
    Drew

    "Nothing in life is to be feared. It is only to be understood."
    --Marie Curie
  • Joseph L. Casale at Sep 3, 2011 at 9:31 am

    Is that the "fast as hell" or "slow as hell" kind? Slow.
    I ask because I have a couple of IBM M5015 (rebranded LSI 9260-8i) controllers that
    I run in RAID-10 and as I'm somewhat on a budget for disks (coming home with $1200
    worth of 15k SAS drives will get me shot) I'd rather run a RAID-5/6 array if the performance
    degradation is minimal. And yes, mine do have the BBU. ;-)

    Not that the performance of an 8x80GB SATA-300 array is much to write home about in the
    first place, but for my purposes it works fine.
    For home, I doubt you would have an issue.

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