Le 27 nov. 2012 à 01:17, Erik Trimble a écrit :
> On 11/26/2012 12:54 PM, Grégory Giannoni wrote:
>> I switched few month ago from Sun X45x0 to HP things : My fast NAS are now
>> DL 180 G6. I got better perfs using LSI 9240-8I rather than HP SmartArray
>> (tried P410 & P812). I'm using only 600Gb SSD drives.
> That LSI controllers supports SATA III, or 6Gbps SATA. The Px1x controllers
> do 6GB SAS, but only 3GB SATA, so that's your likely perf difference. The
> SmartArray Px2x series should do both SATA and SAS at 6Gbps.
The SSD drives I'm using (Intel 320 600GB) are limited to 270MB/sec ; So I
don't think that SATA II is limiting.
> That said, I do think you're right that the LSI controller is probably a
> better fit for connections requiring a SATA SSD. The only exception is
> having to give up the 1GB of NVRAM on the HP controller. :-(
I don't think that this is a real issue when using a bunch of SSDs. I even
wonder if the NVRAM is not slowing down writings. My tests were done with ZIL
enabled, so a power loss shouldn't damage the datas.
> Is the bottleneck the LSI controller, or the SAS/SATA bus, or the PCI-E bus
> itself? That is, have you tested with LSI 9240-4i (one per 8-drive cage,
> which I *believe* can use the HP multi-lane cable), and with a LSI 9260-16i
> or LSI 9280-24i? My instinct would be to say it's the PCI-E bus, and you
> could probably get away with the 4-channel cards. i.e. 4-channels @ 6Gbit/s
> = 3 GBytes/s > 4x PCI-E 2.0 at 2GB/s
The first bottleneck we reached (DL 180 / standard 25 drives bay) was the HP
controller (both P410 AND P812 reached the same perfs : 800MB/sec writing,
With LSI 9240-8I, we reached 1.2GB/s writing, 1.3Gb/s reading.
The LSI 9240-4I was not able to connect to the 25-drives bay ; Not tested LSI
9260-16I or LSI 9280-24i.
The results were the same with 10 or 25 drives, so I suspected either the PCI
bus, either the expander in the 25-drives bay (HP 530946-001).
Plugging the disks directly to the LSI card allowed to gain few MB/s : the
expander was limiting a bit, but moreover, it disallowed to use more than 1
disk controller !
By replacing the 25-drives bay by three 8-drives bays (507803-B21), the system
was able to use 3 LSI 9240-8I, with this 4.4GB/sec reading rate.
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