Questions about hard disks' performance, issues, tips, and software.

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89
votes
2answers
10k views

What are the different widely used RAID levels and when should I consider them?

This is a Canonical Question about RAID levels. What are: the RAID levels typically used (including the RAID-Z family)? deployments are they commonly found in? benefits and pitfalls of each? ...
59
votes
8answers
5k 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 ...
40
votes
3answers
46k views

What are the merits of SAS vs SATA drives? [closed]

What are the merits of buying SAS drives over SATA drives, or vice versa?
38
votes
23answers
6k views

How do I destroy a hard disk?

I have an old hard disk (Maxtor 250Gb) from about 3 years ago that started giving errors and now sits in a draw in my desk. It has some confidential data on it but it's unlikely that it can be read ...
21
votes
13answers
2k views

High Failure Rate of Large Drives?

I recently deployed a server with 5x 1TB drives (I won't mention their brand, but it was one of the big two). I was initially warned against getting large capacity drives, as a friend advised me that ...
13
votes
2answers
5k views

Are RDX removable disks a good replacement for LTO tape?

Over a period of three weeks, I experienced six complete failures of LTO-1 and LTO-2 tape drives at client sites. Some had failed mechanisms. Others lost the ability to write reliably. These were HP ...
15
votes
8answers
4k views

Zeroing SSD drives

We host VPSes for customers. Each customer VPS is given an LVM LV on a standard spindle hard disk. If the customer were to leave, we zero out this LV ensuring that their data does not leak over to ...
5
votes
5answers
7k views

SAS or SATA for 3 TB drives?

We are looking to purchase new 3 TB enterprise-grade drives and can buy either SAS or SATA models. AFAIK, SAS generally gives better performance than SATA, but searching for benchmarks I found ...
4
votes
2answers
242 views

Repartitioning two disks without a loss of data

I am interning at a software company and I have hit somewhat of a brick wall. Here is the deal: The Problem: We have some boxes around here that were incorrectly partitioned for 2 x 500 GB drives. ...
27
votes
9answers
22k views

Reliability of ssd drives

The main advantage of SSD drives is better performance. I am interested in their reliability. Are SSD drives more reliable then normal hard drives? Some people say they must be because they have no ...
21
votes
14answers
19k views

Fastest, surest way to erase a hard drive?

I'm looking for a quick, simple, and effective way to erase the hard drives of computers that my company will be getting rid of (donation to charity, most likely). Ideally, I would like a ...
5
votes
2answers
10k views

How can I set the disk partition alignment using linux tools?

After reading Disk Partition Alignment Best Practices for SQL Server, I just want to give those advices a try, but on my linux test server. What are the required parameters in order to set the ...
31
votes
7answers
38k views

How can I monitor hard disk load on linux

Is there a good command line utility to monitor hard disk load on linux? Something like top but then monitoring disk activity i.s.o. cpu usage. More specifically, I suspect that for some (heavy load) ...
109
votes
4answers
6k views

All servers flooded by salt water, is it possible to recover data from multi-platter drives?

All of my servers are currently flooded by salt water. Is it possible for each platter in a multi-platter drive to be separated, cleaned, imaged, and merged into a new virtual drive for data ...
24
votes
11answers
9k views

Does an unplugged hard drive used for data archival deteriorate?

If I were to archive data on a hard drive, unplug it, and set it on a (not dusty, temperature-controlled) shelf somewhere, would that drive deteriorate much? How does the data retention of an ...
19
votes
4answers
1k views

SSD head / cylinder / cluster details

A customer of ours makes industrial robots that run on very old, but stable, hardware and software. The only bottleneck has always been the hard drive in these moving machines. Due to constant ...
5
votes
5answers
596 views

WipeDrive Utility?

What is the best and fastest wipe drive (zero fill) utility that can be burned to a CD?
9
votes
5answers
75k views

Can you use a USB hard drive in ESXI?

I know that you can install ESXi 4.0 on a thumbdrive, but I was wondering if you could plug in an external harddrive to give extra storage to one of your VMs? We run a fileserver inside of ESXi that ...
4
votes
12answers
14k views

SQL Server database on an external hard disk drive

Due to some security problems, My boss has asked me to store all sensitive data in external/removable storages like USB stick or external HDD and this specially includes the MDF/NDF/LDF files of SQL ...
4
votes
1answer
291 views

How to recreate a RAID 10 array with mdadm

So our virtual machine has broken (it's actually a Linux machine in Azure) on which we were running a RAID10 array of 4 disks. It's an ubuntu box. From what I can tell the four data disks are fine, ...
3
votes
2answers
130 views

Age replacement policy for hard disks and SSDs at servers

I'm planing an age replacement policy for our storage and servers. Most of them are for DBs and some for images (static content) so yes, they have an huge I/O everytime. Also, we use Samsung 840 Pro ...
2
votes
3answers
769 views

Monolithic vs Packaged-based Image Creation

The tried-and-true way of making Mac disk images has been to set up your software perfectly on the newest Mac hardware you have, delete some unnecessary files, and create a (monolithic) image of it. ...
1
vote
1answer
95 views

Can LVM and Traditional Partitions Coexist?

Can you set up a machine in which different drives are formatted as either LVM volumes or as traditional partitions and mix and match the two? For e.g. have the LVM volume mounted as / and /home and ...
2
votes
1answer
252 views

Recover ext3 files from hard disk with bad sector

I have a folder of about 5GB that suddenly disappeared. When I checked its hard disk, I found out it has bad sector for about 2-3MB on this folder. Maybe it is on the folder's pointer. The partition ...
0
votes
3answers
8k views

How long does it take to fsck a volume?

We are running website which is currently serving 3-5 million page views. Our site is file sharing site and so it contains 250,000 files and few thousand symbolic links. The hard disk is a 1500GB ...
0
votes
3answers
568 views

dell 2T 7.2k nearline SAS 6Gbps- ingress/egress throughput

I would like to know, how to calculate sustained read and write speeds supported. I don't have access to machine/drive, but need to define specs to purchase one. What all things would it be ...
0
votes
2answers
359 views

How to mount a second hard drive? Debian

hey, well I mounted my hard drive to var/www/disk2/ but obviously since the first hard drive is on / all the files on var/www/disk2/ are going to count towards the space on the the first hard drive ...
0
votes
4answers
6k views

SATA hdd errors

I have one server with WDC WD3202ABYS ... There are 100 virtual hosts. Server is working about 5 years and in this time period I have change 4 disks. All with same reason: sata error. The last one: ...
-1
votes
2answers
762 views

Do partitions needed to be unmounted when resizing a partition?

I have this article http://www.centos.org/docs/5/html/5.2/Deployment_Guide/s2-disk-storage-parted-resize-part.html which is not clear to me. And also someone told me that swap space does not need to ...
12
votes
2answers
7k views

How to determine the best byte size for the dd command

I know that doing a dd if=/dev/hda of=/dev/hdb does a deep hard drive copy. I've heard that people have been able to speed up the process by increasing the number of bytes that are read and written at ...
11
votes
7answers
3k views

How many SMART sector reallocations indicate problems?

I have a NAS appliance that is just over a month old. It is configured to email me alerts generated from the hard drives' SMART data. After one day, one of the hard drives reported that a sector had ...
8
votes
7answers
16k views

How can I find out what hard disks are attached to a Linux box?

Here's an easy question for you guys: How do I find out what hard drives are attached to a linux box? I'm hoping for a single command that can give me a nice list of all ata/scsi/etc drives. I've ...
10
votes
8answers
7k views

Physically Identify the failed hard drive

So, let's say your server had 6 healthy hard drives. A drive fails (will not mount/detect, drops out of raid with errors) or is failing (SMART getting worse, etc). You need to swap out the bad ...
22
votes
6answers
3k views

Scaling databases with cheap SSD hard drives

I hope that many of you are working with high traffic database-driven websites, and chances are that your main scalability issues are in the database. I noticed a couple of things lately: Most large ...
8
votes
2answers
701 views

How can I split a drive image created with 'dd' into separate files for each partition?

I created an image of a failing drive with: dd if=/dev/sde of=/mnt/image001.dd The drive had only two partitions: Device Boot Start End Blocks Id System /dev/sde1 * ...
7
votes
10answers
15k views

Configuring SQL for optimal performance… SSD or HDD?

Does anyone know of any comparisons that show how SSDs compare to HDDs for performance in a SQL environment? I'm trying to understand what type of performance benefit might be gained by moving to ...
5
votes
4answers
9k views

Performance differences between 2.5“ vs. 3.5” SAS

What real performance gains/losses are there on 2.5" vs. 3.5" 15k SAS drives. Are folks really seeing seek differences, &c?
5
votes
8answers
6k views

Hard Drive Speed: RPM vs. Cache

When trying to choose a SATA magnetic hard drive (not SSD) for high performance for both random and linear access, which should be the primary factor? For example: would a 10k RPM drive with 16MB ...
16
votes
6answers
4k views

What's the effect of standby (spindown) mode on modern hard drives?

I just assembled a new Linux file server with several Samsung HD103UJ 1TB hard drives and I am currently optimizing it. The question I can't find an answer to is: is it reasonable to set a spindown ...
9
votes
6answers
7k views

Is bit rot on hard drives a real problem? What can be done about it?

A friend is talking with me about the problem of bit rot - bits on drives randomly flipping, corrupting data. Incredibly rare, but with enough time it could be a problem, and it's impossible to ...
5
votes
3answers
3k views

RAID 5 with big SATA disks. Do or don't?

Is it sane to build a machine with RAID 5 expecting to hold around 5 Tb (and able to grow) with 1.5 or 2 Tb SATA II disks? It will be used as audio and documents storage. I already have chosen a ...
5
votes
8answers
2k views

Best places to free space on Windows? [closed]

Prompted by Adam.. I would like your suggestions as to freeing up space on a Windows machine. Yes, yes, I know disk space is cheap but sometimes, you have older machines that just need more space and ...
4
votes
5answers
2k views

The difference between desktop-series HDD drives and server-series

What are the main differences between desktop-series hard disks and server-series? The obvious things I can see are: durability (server hardware mostly more qualitative and have more warranty) and ...
2
votes
7answers
730 views

how to track down permanent disk accesses on linux

I have a machine that runs few services, but I don't believe they are responsible for sometimes heavy disk access on this server (massive head moving which I can hear, after long periods of almost no ...
16
votes
2answers
2k views

RAID-6: better to replace two dead drives at the same time, or one at a time?

We have a 16-drive RAID-6 that has three problem drives. Two are already dead, and the third is giving SMART warnings. (Nevermind how it got in such a bad state.) Obviously we want to replace the ...
9
votes
2answers
3k views

Is sata 2 backwards compatible with sata 1

Simple question, Is SATA 2 compatible with SATA 1.
8
votes
3answers
25k views

SAS vs. Nearline/MDL SAS - What is the difference?

As subject I guess, looking at SAN's and most vendors offer 10k or 15k "proper" SAS drives, many also offer 7.2k MDL/Nearline SAS drives. Does anyone have an authoritative explanation of the ...
6
votes
6answers
7k views

Linux ATA errors: Translating to a device name?

When a Linux box gets an ATA error, it syslogs it with a message identifying the disk as "ata%d.00". How do I translate that to a device name (e.g. /dev/sdb)? I feel like this should be trivial, but I ...
4
votes
2answers
567 views

How to know which disk has failed on a Mirrored Raid? marked as DR0

Our 2ndry DC, which is on a W2K8R2 Mirrored software raid has lost it's sync, and disk management displays the failed redundancy error How do I know which of the disks has failed? (beside to try ...
4
votes
7answers
11k views

Disk usage per user in Linux / Unix

I need to find out how much disk space is being occupied by each user on the network. I am aware of df and du commands: I could list the entire filesystem and AWK the output, but I wonder if there is ...