[BBLISA] Fileserver opinion

[Mark Niedzielski]

I am unfamiliar with the exact state of FreeBSD drivers, but I can make
recommendations for ZFS hardware on Solaris.

In short, you can't go wrong with the latest generation of LSI cards
(92xx-series).  This appears to be common wisdom and certainly my
experience.  The cards are available in two variants, HBA and RAID.  The
HBA cards behave as you expect.  The RAID cards can be run in IT (HBA)
or IR (RAID) mode.  In IT mode, the RAID versions of the card behave
like the HBA version but with a faster processor and more on-card
cache.  I am unaware of any benchmarks on performance differences.  But
please share them if you find them.  All support a BBU - use it.

This exchange covers some of the specifics: 
http://www.natecarlson.com/2010/08/23/lsi-command-line-utility-for-sas2-non-raid-controllers/

I'll also recommend Greg Smith's recent book, "*PostgreSQL 9.0 High
Performance" for its discussion on controller choices.  You can find the
relevant chapter as a free download.  But I recommend the entire book
for its good coverage of the current state of general tuning of POSIX
systems.*

My experience with 3ware is they not well supported and poor choices for
ZFS.  I have mixed experience with Areca.  The hardware seems good, but
I found the drivers were not sufficiently developed to get top results. 
My other experience is with the various Marvell cards from SuperMicro. 
The first generation behaved well but had mediocre performance.  The
lastest ones are decent and certainly very good for the price.  Just
check the chipset - not all have BSD/Solaris drivers.

I have moved exported ZFS pools between Marvell and LSI cards with success.

And as for your original question regarding SAS vs SATA performance:  my
experience is pool configuration, type of PCI bus, and drives/controller
can make more difference than drive speed - its the old question of
maximizing throughput with a balanced system.  Smith gets into this a
bit as well.  Have you considered 10k SATA drives?

- Mark Niedzielski


On 11.6.24 16:13 , John P. Rouillard wrote:
> In message <BANLkTin=PQga7R4us208j5iZxD-eQy+JSA at mail.gmail.com>,
> Daniel Feenberg writes:
>> We have been using ZFS under FreeBSD for a while, and are very pleased,
>> but are considering building a system with SAS drives, in the hope that they
>> will be faster (any truth to that?). I am assuming that I should look for a
>> non-RAID controller, but I can't find any SAS controllers that don't claim
>> to do RAID and are on the FreeBSD compatibility list. I have always thought
>> that using a RAID controller for a non-raid partition was a bad idea, since
>> it limited ones ability to swap controllers. Is that prejudice justified?
> Probably. Some raid controllers can be set to jbod/passthrough mode
> which should eliminate any "raidish" remnants. I did set up a software
> raid 10 on 3ware hardware with SATA disks in passthough mode and was
> able to move it to a system using the motherboard SATA connectors and
> get it working. YMMV.
>
> But if the raid controller tries to manage the disk rather than just
> say here it is they usually have their own format for the drives which
> locks you into that brand controller if not a specific family of
> controllers.
>
> One thing we use at $WORK are lsi cards where we created a striped
> (logical) volume/disk with a single physical disk. We did this when we
> couldn't get jbod mode to work (or wasn't supported on the card). I
> have no clue how/if I can reuse them without the lsi card.
>
> --
> 				-- rouilj
> John Rouillard
> ===========================================================================
> My employers don't acknowledge my existence much less my opinions.
>
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