Hardware RAID support? Which controller best to use?

Nathan Vidican nvidican at wmptl.com
Fri Nov 18 19:00:21 GMT 2005

ray at redshift.com wrote:
> | I'm trying to get him towards ordering a 3Ware-Escalade 9500S-4 RAID 
> | controller (or possibly the -8 or -12 one).
> The 9500S line is a good choice.  You can also sometimes find them used/NIB on
> ebay at a fair price ($300 to $400).  BTW, in my testing, you don't get much
> additional performance from having 8 vs 4 drives (if you want to save costs).
> Although you do get more space :)  
> | One thing which is of importance is that their budget may not allow for 
> | a really high end server, so they may have to decide to buy a semi 
> | high-end server. This then may result in them taking Athlons instead of 
> | Opterons, and it may result in a MoBo with 32-bits PCI slots instead of 
> | 64-bits PCI slots. Judging from the pictures of the 9500S it has a 
> | 64-bits PCI slot, but it looks like it might be compatible with the 
> | 32-bits slots as well (at a performance penalty, of course).
> | Would you happen to know if that's indeed possible, or whether they'd 
> | better choose a different RAID controller?
> You'd have to check the 3ware website to be sure, but a lot of times those cards
> are backwards compatible with the 32 bit slots.  I just checked the manuals I
> have for the 9000 series and it says 3Ware cards will run properly in any PCI or
> PCI-X slot, but you'll get better performance in a 64 bit slot - here is the
> text from the manual:
> --------------------------------------------------------
> Selecting the Slot in Which to Install the Controller
> Consider these factors when deciding on the slot in which to insert the controller:
> .. While the 3ware RAID Controller runs properly in any PCI or
> PCI-X slot, not all slots give equal performance due to the
> architecture of the PCI bus.
> These slots typically give the best performance:
> .. Slots closest to the Accelerated Graphics Port (AGP), if
> included.
> .. 64-bit PCI slots
> Although the controller fits in both 32-bit and 64-bit PCI or
> PCI-X slots with 5V as well as with 3.3V, install it in a 64-
> bit slot to take full advantage of the controller’s
> performance.
> --------------------------------------------------------
> | Regarding the MySQL versions and their settings: tnx for giving me 
> | enough comfort to indeed give heavy preference for the FreeBSD amd64 
> | version. Will (source) installing the version from the ports do, or do 
> | you mean something else when you say that you compiled MySQL yourself?
> from the tar.gz off the mysql site.  E-mail me privately for a full run down on
> the install I use, but here is the basic idea:
> as root do this:
> ------------------------------------------------------
> tar -xzf mysql-4.1.15.tar.gz
> cd mysql-4.1.15
> pw groupadd mysql
> adduser {user you are creating is mysql}
> CFLAGS="-O3" CXX=gcc CXXFLAGS="-O3 -felide-constructors -fno-exceptions
> -fno-rtti" ./configure --prefix=/usr/local/mysql --enable-assembler
> --with-mysqld-ldflags=-all-static --without-debug
> make
> make install
> make clean
> ln -s /usr/local/mysql/share/mysql/mysql.server /usr/local/bin/mysql.server
> ln -s /usr/local/mysql/bin/mysql /usr/local/bin/mysql
> ln -s /usr/local/mysql/bin/mysqld_safe /usr/local/bin/mysqld_safe
> ------------------------------------------------------
> There is more too it, but that's the basic idea.  Check the readme/install files
> with the tar.gz - I will also send you my entire run down privately in a second.
> | Regarding the benchmark results: I'd love to receive them. Can you 
> | perhaps send them off-list to me?
> Actually, I forgot that I put them on-line a while back.  Here you go:
> http://www.redshift.com/~ray/mysql_bench/
> | Regarding W*nd*ws vs. FreeBSD: I love your remark; I wonder if the 
> | person I forwarded it to can laugh as loudly about it as I did. :D
> :)
> | Finally regarding SCSI vs. SATA:
> | >I've had far better luck using SATA over SCSI in the recent couple of years.
> | > We have several machines setup using FreeBSD and 3Ware RAID 0+1 that 
> | > routinely run with no problems and uptimes of 200 to 300 days at a time.
> | 
> | Very interesting to know. At present, I myself have a 754 socket AMD 
> | Athlon 64 3.2 GHz (IIRC), running FreeBSD 5.4 release AMD-64, with an 
> | Adaptec 2200S U320 SCSI RAID controller with 4 Maxtor Atlas 10KIV 36GB 
> | drives attached to it in RAID-10 mode. So far it works a charm (though I 
> | too had to effectively downgrade it to U160 due to the lack of 64-bits 
> | PCI slots, grrr). I hope it'll keep performing well (so far uptimes in 
> | the order magnitude you mention have been working fine for me as well on 
> | SCSI - Adaptec 2100S RAID set-ups in my (now) fall-back server, and ever 
> | after installing the AMD-64 one 34 days ago I haven't had to restart it 
> | so far)...
> The file will send you with the benchmarks includes the PHP files to run the
> benchmarks, so if you feel like adding your #'s to the mix, just let me know.
> Or feel free to run the code and send me the results.  I'll e-mail you privately
> in a second here.
> | Yet, it'll be interesting to keep an eye on the SATA RAID performance 
> | and costs. With such uptimes SATA will surely become (if it hasn't 
> | already become so, that is) a very good alternative for SCSI.
> SATA is built on top of SCSI I think (not sure exactly how it all sorts out, but
> I think some of the SATA stuff is tied into some of the SCSI stuff in the kernel
> or something).  If I recall correctly, you have to leave some SCSI drivers in
> the kernel when you setup SATA on FreeBSD.  I may be off, but I think that's
> what we had to do.  Maybe someone more familiar with the kernel stuff can
> comment further on that count.
> I will e-mail you the install run down in a sec.
> Ray
Actually, that's quite wrong. S-ATA is ATA, not SCSI-like... S-ATA in fact is 
almost the same as ATA (EIDE) from a code/kernel standpoint. The physical 
hardware interface differs slightly and offers greater stability and performance 
than standard ATA (EIDE). However, you are correct if not confusing when you 
state that you must 'leave some SCSI drivers in the kernel', this is not for ATA 
so much as it is for the use of the RAID card. If you're using plain old S-ATA, 
no SCSI disk devices are required, but with the 3Ware Escalades, you will need:

device scbus
device da
device twa

Anyhow, long story short - the only 'real' difference from S-ATA to P-ATA 
(Parallel ATA aka 'ATA' or 'EIDE'), is the interface - the drive internals and 
functionality are the same - but both differ from SCSI.

Nathan Vidican
nvidican at wmptl.com
Windsor Match Plate & Tool Ltd.

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