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TL;DR Is the RAID controller on the HP ProLiant DL360 G7 known to be slow or problematic? My RAID0 set is performing horribly.

I have an HP ProLiant DL360 G7. It came with a 160GiB SAS HDD, and I created a logical disk for it and set up Ubuntu Server on there. I inserted three consumer-grade SSDs (ADATA Premier SP550 960GB) that I knew worked with this server and created a RAID0 logical drive in ORCA including just the three SSDs. I then made the mistake of loading my entire 500GiB database on there, a long process, before I had run any benchmarks.

These SSDs are supposed to get 500GiB/s read... each. I've got 2 in RAID0 (using the Linux software RAID) on a consumer-level machine, and I see 1000GiB/s read with hdparm -t. I'd think 3 in RAID0 on the server would get 1500GiB/s.

I get ~210MiB/s read on that SSD array, wow. Yes, I made sure to run the test with the database stopped and nothing else running. I've heard bad things about hardware RAID in the past. Is the RAID controller on this machine just slow? It'll be a big pain to migrate the DB, put each SSD into a separate logical disk, then set up the Linux software RAID, but I'm considering doing it.

Update: I've added a battery-backed-up disk cache module. Now seeing 648MiB/s with hdparm, which I know isn't the best benchmark to use. So I tried running my actual workload on this machine, i.e. a process that repeatedly runs different heavy PostgreSQL queries concurrently, 24 at a time. I'm not seeing a disk bottleneck anymore. I suppose my problem is solved for now.

sudo
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  • That server comes with a P410 smart array controller, right? Then this Q&A may be of interest: http://serverfault.com/a/431456/37681 Also please be aware that `hdparm -t` is not a proper disk benchmarking tool – HBruijn Jul 08 '16 at 18:13
  • Not tempted to use a supported configuration? serverfault is for professional sysadmins, we say that when you sign up – Chopper3 Jul 08 '16 at 18:24
  • @HBruijn Yes, it does. Thanks, that thread has some useful info. I did also run my actual tasks on the server and saw them running obviously more slowly than on the consumer-level machine. – sudo Jul 11 '16 at 22:20
  • @Chopper3 Nothing unprofessional going on here. We're on a budget and need fast SSDs for something that doesn't need to be reliable. We can't pay for HP SSDs. But the ProLiant has good CPU performance for the price, so we have one (will possibly get more) for certain tasks. – sudo Jul 11 '16 at 22:36

2 Answers2

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That's a pretty old RAID controller (those were introduced in 2010, I think?), and its throughput characteristics were designed for spinning disks, not SSDs.

You might be bottlenecking on older gen SATA, or the RAID controller itself - but either way, that RAID controller isn't worth wasting your time on, performance-wise.

Shane Madden
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This should be a comment, but its a bit long.

with the database stopped

It's a very unusual database which runs optimally on RAID 0

It's also somewhat unusual to spend so much money on a server and plan no resilliency for the storage. But to then compound that, by using raid 0 means you are three times more likely to loose all your data than with a single disk.

Update: I've added a battery-backed-up disk cache module.

Erk! The only reason for using a hardware raid controller is to provision non-volatile write caching!

I look forward to your next question on how to make toast in a bathtub.

symcbean
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  • Jokes aside, do you have any practical tips on making toast in the bathtub? – Dylan Knoll Jul 22 '16 at 20:30
  • There's no reason to assume what we're using this server for. As I said already, we don't care about the database being reliable, just about it being fast. It doesn't need to be up 24/7, and we have backups. It's not serving anything real-time. – sudo Jul 22 '16 at 22:24
  • Also, "the only reason for using a hardware raid controller is to provision non-volatile write caching?" That's a pretty broad statement to make when there are so many hardware and software RAID systems out there. I'm going to test and see which is faster. BTW, I need the BBWC to even use software RAID since you can only create two logical disks without it (which wasn't in the documentation, ugh), and one logical disk is for the OS only. – sudo Jul 22 '16 at 23:03