RAID solution with hardware assistance. RAID parity calculations can be performed by either the main CPU, or by a separate processor on the RAID controller card.

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65
votes
8answers
7k views

How can a single disk in a hardware SATA RAID-10 array bring the entire array to a screeching halt?

Prelude: I'm a code-monkey that's increasingly taken on SysAdmin duties for my small company. My code is our product, and increasingly we provide the same app as SaaS. About 18 months ago I moved ...
22
votes
3answers
9k views

Linux - real-world hardware RAID controller tuning (scsi and cciss)

Most of the Linux systems I manage feature hardware RAID controllers (mostly HP Smart Array). They're all running RHEL or CentOS. I'm looking for real-world tunables to help optimize performance for ...
21
votes
4answers
1k views

Do raid controllers syncronize HDD platter rotation?

I'm in the market for a new storage solution. While researching various specs one of my coworkers said that some raid controllers can synchronize HDD rotation to the effect of all drives' sector/block ...
17
votes
3answers
4k views

How effective is LSI CacheCade SSD storage tiering?

LSI offers their CacheCade storage tiering technology, which allows SSD devices to be used as read and write caches to augment traditional RAID arrays. Other vendors have adopted similar ...
16
votes
8answers
8k views

RAID-5: Two disks failed simultaneously?

We have a Dell PowerEdge T410 server running CentOS, with a RAID-5 array containing 5 Seagate Barracuda 3 TB SATA disks. Yesterday the system crashed (I don't know how exactly and I don't have any ...
13
votes
1answer
4k views

Hardware RAID controller cache battery failure frequency/lifetime?

I'm in an environment that contains many Supermicro servers equipped with Adaptec and LSI MegaRAID hardware RAID controllers. These controllers contain battery-backed cache modules to help boost write ...
12
votes
11answers
2k views

Is RAID5 more robust than RAID1

I am about to replace an old hardware RAID5 array with a Linux software RAID1 array. I was talking to a friend and he claimed that RAID5 was more robust than RAID1. His claim was that with RAID5, on ...
12
votes
5answers
3k views

ZFS best practices with hardware RAID

If one happens to have some server-grade hardware at ones disposal, is it ever advisable to run ZFS on top of a hardware-based RAID1 or some such? Should one turn off the hardware-based RAID, and run ...
10
votes
7answers
27k views

What is a (raid-controller-) BBU for?

I am wondering what's the purpose of a BBU. My first understanding was, that it enables the cache to write the data to the disc during a power failure. But some specifications say that a BBU can hold ...
9
votes
1answer
2k views

Managing battery relearn cycles on LSI and similar RAID controllers

How do engineers deal with RAID controller battery "relearn" cycles? As noted in: What's a "battery relearn" on a LSI MegaRaid?, relearn cycle discharges the RAID controller battery ...
8
votes
5answers
4k views

Software vs. Hardware RAID1 (Mirror)

How does the Software Mirror in Windows Server systems compare to an affordable hardware/BIOS RAID? I've had some rather bad experiences with onboard hardware RAID controllers, so I would want to ...
7
votes
4answers
14k views

Why do I need a raid battery pack?

I'm trying to understand why one would add a batterypack to a raid card. It seems to me like if power goes down, running just the raid card is going to do little good: without power for HDs and ...
7
votes
3answers
21k views

HP ACU CLI Examples

Has anyone used the HP Array Configuration Utility Command Line Interface (hpacucli.exe) to get physical disk information into a file? I'm not at the machine right now, but basically I want to find ...
7
votes
8answers
699 views

Recommendations for hardware RAID controllers [closed]

I'm looking for a hardware RAID controller. I want something that: Can support 8 or maybe 16 hard drives Won't randomly break, lose my data, etc. Does anyone have recommendations? It seems like ...
7
votes
3answers
685 views

RAID array Considerations - Any advice?

We just bought a Dell PowerEdge r510 (12 drive bays) that will fill the role of an archive server. We have 6 drives (1TB each) installed. The plan is to have all the drives in a single RAID array and ...
7
votes
3answers
857 views

Do disks in Raid-1 function outside of the raid?

Raid-1 is mirroring two disks (if I haven't messed up completely here :p). Does that mean that I could take one disk out and put it into another machine and it would work like a normal disk? Or does ...
7
votes
2answers
353 views

Are different RAID cards setups compatible?

I'm setting up a new NAS/SAN system with RAID5, and I was wondering if going the software or hardware RAID way because I had this question in mind: If my hardware-RAID card fails, will I need to ...
7
votes
4answers
61k views

How to check if hardware RAID is configured?

I have several servers running Windows 2008 and Red Hat 5 that are capable of hardware RAID. How do I check that hardware RAID is configured?
7
votes
2answers
1k views

Can enabling a RAID controller's writeback cache harm overall performance?

I have an 8 drive RAID 10 setup connected to an Adaptec 5805Z, running Centos 5.5 and deadline scheduler. A basic dd read test shows 400mb/sec, and a basic dd write test shows about the same. When I ...
7
votes
1answer
3k views

How to select the best Stripe Size when configuring a RAID Array

There are various "references" on the Internet that delve into some discussion about what factors to consider when selecting a particular RAID stripe size (4KB to 128KB or more) for an array of disks, ...
7
votes
1answer
482 views

LSI RAID controller errors on DB import - How to troubleshoot?

We're running an import of a database dump on an Oracle system - (RHEL 5.9, 2.6.18-348.6.1.el5). The import does not complete, eventually erroring-out with: ORA-15080: synchronous I/O operation to a ...
6
votes
5answers
8k views

Poor read performance on Dell Perc H200 RAID10 with (4) 1TB 7200rpm 64MB drives

I am seeing only 50MB/s reads: ensnare@box:~$ sudo hdparm -tT /dev/sda [sudo] password for ensnare: /dev/sda: Timing cached reads: 4592 MB in 2.00 seconds = 2296.48 MB/sec Timing buffered disk ...
6
votes
3answers
625 views

Would unplugging a drive simulate a drive failure?

I just set up a RAID 1 array, 2 2tb drives mirrored. I am wondering what will happen if one were to fail. Would unplugging one of them be a valid test? I am using the Onboard controller of an asus ...
6
votes
2answers
2k views

Why are “sectors per track” still relevant on a modern OS with modern drives?

I am building out a new machine and the raid controller is asking me for sectors per track. I haven't had to deal with disk math in a long time (1998?), and I can't find anything that pertains to ...
6
votes
2answers
3k views

How long should rebuilding 250GB take? [closed]

In a PowerEdge 1900 have I a hardware RAID 5 of 5x250GB disks + 1 hot spare 250GB. Disk 2 have errors, so I forced it offline in the raid bios to replace it. Now it have been rebuilding to the hot ...
6
votes
1answer
1k views

I have a 21TB array but only 16TB is visible from Windows

CONTROLLER Raid Controller: 3Ware 9650SE-24M8 Disks: 21 x 1TB RAID5 Stripe 64KB WINDOWS OS: Windows Server 2003 SP2 32x Disk: Dynamic 19557.44GB Volume: Capacity 15832.19GB I guess my array ...
6
votes
4answers
10k views

Monitoring hardware RAID on VMWare ESXi

I've got an ESXi 3.5 server on "unsupported" hardware - SuperMicro motherboard, Adaptec 9410 3405 RAID controller (oops, the 9410 is the onboard controller that's not being used for RAID) - and I'm ...
6
votes
1answer
277 views

How do you connect more than 4 drives to a LSI 9361-4i MegaRAID controller?

I’m fairly new to proper hardware RAID having only used it in pre-built server machines before, but on the recommendation of some friends who work for datacentres I’ve bought an LSI 9361-4i MegaRAID ...
6
votes
1answer
616 views

Areca - expanding a raid by swapping out disks for larger ones

What I am looking to do is, one by one, replace the drives in my current raid array (in a 1680i). After the drives are replaced by their larger counterparts, I want to do an online expand of the ...
6
votes
1answer
270 views

Replace HP Smart Array E200i without losing data

I've got a Smart Array 200i which seems to have some bad slots (slot 3 and slot 5). It doesn't matter what HD I put in these slots, it keeps telling me the drive is bad. My question is two-fold: Is ...
5
votes
5answers
1k views

RAID level confusion (MegaCli vs megasasctl output)

I'm utterly new to working with LSI MegaRAID controllers and I'm confused as to what RAID level I am actually running. My server is equipped with 4 disks, 4TB each and I would like to have them ...
5
votes
4answers
8k views

Is this a critical RAID error?

If I do the following /opt/MegaRAID/MegaCli/MegaCli -LDInfo -Lall -aAll -NoLog > /tmp/tmp /opt/MegaRAID/MegaCli/MegaCli -LDPDInfo -aAll -NoLog >> /tmp/tmp then I see these errors ...
5
votes
2answers
2k views

Linux: How to align partition and file system on hardware RAID

I have a test box (PowerEdge 2950) with a Perc 6/i and 4x 15.5k SAS drives attached (with 512 byte block sizes). These are in a single RAID 5 virtual disk with a 64KB chunk size. I am creating a ...
5
votes
2answers
2k views

LSI 9260-8i w/ 6 256gb SSDs - RAID 5, 6, 10, or bad idea overall?

We're provisioning a new production server for our reasonably busy website. Our choice of host have available a 6 drive configuration with a LSI 9260-8i card. My initial thought was to fill all six ...
5
votes
3answers
1k views

Four disks - RAID 10 or two mirrored pairs?

I have this discussion with developers quite often. The context is an application running in Linux that has a medium amount of disk I/O. The servers are HP ProLiant DL3x0 G6 with four disks of equal ...
5
votes
1answer
140 views

what harm can writeback caching have on a degraded disk array?

At work I administer several machines using (real) hardware raid controllers (with battery backed write caches), and these have the nasty habit of falling back to writethrough behaviour when an array ...
5
votes
4answers
993 views

IBM ServeRAID: how to use email alerts?

I just installed a brand old IBM server with a ServeRAID 4Lx card. I installed the driver, and the ServeRAID manager software v9.30. Everyting works as expected. My problem is: Yesterday, when ...
5
votes
2answers
1k views

PERC 6/i | ext4 | raid5 | 4 disks - improve write performance

I am running several fileservers using this controller, filesystem and disk setup. All of them are suffering from poor write performance, once the 256MB BBU Write Cache is full i get really high ...
5
votes
4answers
1k views

Poweredge RAID Monitoring and Debian

What tools do you use to monitor hardware RAID Status on Dell Poweredge 2950 (II and III, perc)? I run Debian. I've used a "debianized" version of dell openmanage in the past. I'm looking for a ...
4
votes
4answers
3k views

Is it normal for a SAS drive to have a few bad blocks, or should I replace my drive ASAP?

I have a drive—part of a RAID 1 mirror—that has two bad blocks. Adaptec Storage Manger e-mailed me when it detected the blocks. It shows 4 medium errors for that drive, but state is still “optimal”. ...
4
votes
1answer
243 views

Dell 2950 - Can I mix SSD with spindle HDDs?

I have a Dell 2950 with a Perc 5/i controller inside it. I don't want to spark a debate about drive types and which is "better" etc etc. Just simply; I would like to put in 2x Cheetah 15.5k SAS ...
4
votes
2answers
201 views

SAS internal cable compatability

In the office, we've elected to whitebox go with a commodity approach to a certain class of server we'll eventually need a lot of. It's time to consider picking up a few more. It has been a year since ...
4
votes
3answers
547 views

Defragment an Exchange Volume

The Scenario: I use a dedicated volume (RAID volume) to store all of my data for my Exchange 2007 server. Today, out of curiosity, I decided to check up on how fragmented the files on this data ...
4
votes
1answer
527 views

How to update SSD Firmware on RAID Controllers

Got some servers with RAID Controllers and SSD. Raid Controller: LSI MegaRaid 9271-4i SSD: Intel 520 The MegaRaid controllers have the ability to update drive firmware using MegaCLI. Intel for ...
4
votes
2answers
618 views

Write caching in linux

I have read a lot on serverfault and searched on google about write caching, but still cant find the answer. I have an HP ProLiant DL380 G5 with HW raid with 512 MB Battery backed cache. I use debian ...
4
votes
6answers
3k views

What is the best way to RAID external drives?

I love the fact that you can now buy 1 and 2 TB drives cheap. However that much data on a single drive scares me. What would be the best way to build a raid system out of external drives? I am looking ...
4
votes
1answer
113 views

Partition alignment on MegaRAID RAID 1 with 4k sector (advanced format) drives

I want to setup RAID 1 (mirroring) on a LSI MegaRAID SAS 8708EM2 (1078 chipset) with 4k sector (advanced format) drives. To the best of my knowlegde the controller does not officially support 4k ...
4
votes
1answer
576 views

Areca RAID volume and LVM alignment

I have the following hardware: 1x - Areca ARC-1680IX-24 PCIe x8 SAS RAID Card 24x - Seagate Barracuda LP 2 TB 5900RPM SATA 3 GB/s 32 MB Cache 3.5-Inch Internal Hard Drive ST32000542AS I plan on ...
4
votes
1answer
240 views

Possible to migrate RAID 10 system from 2TB Seagate to 2TB WD?

A couple of our servers have ST32000641AS (2TB Seagate desktop drives) in RAID 10 using an Adaptec 2405 controller. I've been told by Adaptec that this is a bad idea and we have, in fact, already ...
3
votes
4answers
661 views

Dell R320 RAID 10 with CacheCade

I'm looking for a higher-performance build for our 1RU Dell R320 servers, in terms of IOPS. Right now I'm fairly settled on: 4 x 600 GB 3.5" 15K RPM SAS RAID 1+0 array This should give good ...