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

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144
votes
2answers
28k 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?
118
votes
4answers
7k 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 recovery?...
82
votes
8answers
12k 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 ...
72
votes
17answers
13k views

Does orientation affect hard drive lifespan?

Are there any studies or evidence which show that mounting a hard drive horizontally is better than vertically for the lifespan of the device? Or upside down, or any direction for that matter.
59
votes
8answers
90k 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) ...
55
votes
8answers
4k views

What are the advantages of tape drives?

IBM still develop and sell tape drives today. The capacity of them seems to be on a par with today's hard drives, but the search time and transfer rate are both significantly lower than that of hard ...
48
votes
7answers
18k views

How can I successfully mount an 8-bit SCSI drive on a modern computer?

I have a number of internal 8-bit SCSI-1 drives that I'd like to archive for historical purposes. These are all the old NeXT Cubes and NeXTStations (monochrome and color) that were used by id ...
44
votes
23answers
9k 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 ...
44
votes
3answers
50k 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?
41
votes
10answers
7k views

Linux on VMware - why use partitioning?

When installing Linux VMs in a virtualized environment (ESXi in my case), are there any compelling reasons to partition the disks (when using ext4) rather than just adding separate disks for each ...
40
votes
6answers
4k views

Is my Hard Drive Failing?

I just tried to run a test on my hdd and it doesn't want to complete a self test. Here is the result: smartctl --attributes --log=selftest /dev/sda smartctl 6.2 2013-07-26 r3841 [x86_64-linux-3.13.0-...
37
votes
11answers
15k 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 ...
35
votes
10answers
15k views

How should I burn in hard drives?

Google did a very thorough study on hard drive failures which found that a significant portion of hard drives fail within the first 3 months of heavy usage. My coworkers and I are thinking we could ...
35
votes
2answers
2k views

Unable to write to disk but disk isn't full

I am using Ubuntu 12.04 and can't write to any file, even as root, or do any other operation that requires writing. Neither can any process that needs to write, so they're all failing. df says I've ...
33
votes
14answers
11k views

Is it safe to store data on a hard drive for a long time?

Is it safe to backup data to a hard drive and then leave it for a number of years? Assuming the file system format can still be read, is this a safe thing to do. Or is it better to continually ...
31
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 ...
29
votes
2answers
12k views

Why are enterprise SAS disk enclosures seemingly so expensive?

I will begin by stating that I do not believe this is a duplicate of Why is business-class storage so expensive?. My question is specifically about SAS drive enclosures, and justifying their expense. ...
28
votes
9answers
10k views

To improve SQL performance, why not just put lots of RAM rather than having faster hard disks?

People keep telling me that in order to improve an SQL server's performance, buy the fastest hard disks possible with RAID 5, etc. So I was thinking, instead of spending all the money for RAID&...
26
votes
8answers
5k views

Consumer (or prosumer) SSD's vs. fast HDD in a server environment

What are the pro's and con's of consumer SSDs vs. fast 10-15k spinning drives in a server environment? We cannot use enterprise SSDs in our case as they are prohibitively expensive. Here's some notes ...
26
votes
8answers
16k 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 detect....
25
votes
6answers
11k views

Is a hard drive's serial number globally unique?

On Linux I can use smartctl to get a hard drive's vendor, model, firmware revision and serial number: # smartctl -a /dev/sdb smartctl 5.40 2010-07-12 r3124 [x86_64-unknown-linux-gnu] (local build) ...
24
votes
8answers
2k views

How do I protect business critical data against fire?

We have 72 hard drives that contain our webcast inventory. The number is increasing. We're located in a frame building and we are afraid of not only fire, but catastrophic fire. I've priced fireproof ...
24
votes
2answers
2k views

What does SMART testing do and how does it work?

man smartctl states (SNIPPED for brevity): The first category, called "online" testing. The second category of testing is called "offline" testing. Normally, the disk will suspend offline ...
24
votes
6answers
4k 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 ...
24
votes
2answers
7k views

Reliability of SSD vs HDD (Over large temperature variations)

I've got an application which requires data recording in a outdoor environment, and I am interested in the reliability of SSDs vs HDD when placed in a cold (down to -20) and hot (+50) ambient ...
23
votes
14answers
35k 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 single-...
23
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 ...
23
votes
2answers
17k views

Is it possible to on-line shrink a EXT4 volume with LVM?

Today I tried this on my machine with OpenSUSE 12.3 (kernel 3.7): # resize2fs /dev/mapper/system-srv 2G resize2fs 1.42.6 (21-Sep-2012) Filesystem at /dev/mapper/system-srv is mounted on /srv; on-line ...
22
votes
4answers
2k 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 ...
22
votes
3answers
53k views

Setting Low Disk Space Alerts on Windows Server 2008

I was wondering if there is an easy way to trigger an e-mail alert on Windows Server 2008 when any logical disk partitions become low on space. I have 2 SQL servers that have come close to running ...
22
votes
3answers
22k views

CentOS thinks Disk is busy, can't mount or fsck

I'm a longtime user, and first time question submitter. I've spent a full day searching this and many other sites for a solution, but I must resort to requesting assistance to resolve my situation. ...
21
votes
8answers
581k views

How to format as FAT32 from Windows 7/Vista

What is the best way to format a USB drive with FAT32 (for Mac compatibility) from within Windows 7/Vista? I ask because the Disk Management only lets you pick exFAT (because the disk is over 32GB I ...
21
votes
2answers
3k views

In Linux, why isn't superuser root's folder under /home?

You can create a user that has privileges like root, and it's home directory will fall under /home/username. Why does root get its own folder at the top level of the file system? Is this just ...
21
votes
5answers
3k 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 ...
21
votes
8answers
576 views

Server vendor that allows 3rd party disks

As noted here, Dell is no longer allowing 3rd party disks to be used with their latest servers. As in, they don't work period. Which means that if you buy one of these boxes and want to upgrade the ...
21
votes
1answer
278 views

Is it possible that just one bit switches so my file shows me a letter “Q” instead of a “S”

In our application we use Hibernate and PostgreSQL to store data. In one of our database tables we have a discriminator column which says for example "TIPPSPIEL". It is a fixed string and can not be ...
20
votes
4answers
2k views

Why would a heavily disk intensive application run faster on a SAN than on a Physical Disk?

Why would a heavily disk intensive application run faster on a SAN than on a Physical Disk? I would have expected the Physical disk to be slightly faster but in fact the process ran 100 times faster ...
20
votes
7answers
24k 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 ...
20
votes
6answers
8k 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 ...
20
votes
3answers
19k views

limit linux background flush (dirty pages)

Background flushing in linux happens when either too much written data is pending (adjustable via /proc/sys/vm/dirty_background_ratio) or a timeout for pending writes is reached (/proc/sys/vm/...
19
votes
3answers
515 views

Replacing Hard Drives [closed]

I was wondering if it is a good idea to replace a hard drive in a (fairly) system-critical database server after a certain number of years of use, before it dies. For example, I was thinking of ...
19
votes
3answers
6k 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 ...
19
votes
3answers
2k views

Can “enterprise” drives be safely replaced by near/midline in some situations?

When specifying servers, like (I would assume) many engineers who aren't experts in storage, I'll generally play it safe (and perhaps be a slave to marketing) by standardising on a minimum of 10k SAS ...
18
votes
14answers
10k views

How can I destroy data on a failed hard disk without voiding warranty?

Suppose I have a hard disk with data I don't want to expose to a third party. The warranty period for that disk still lasts. Now the disk starts malfunctioning. I can't use a disk wiping program on a ...
18
votes
4answers
22k views

Intro to Laptop Hard Drives

I've had my first notebook hard drive death (well, actually, it's currently dying... clicking noises, super slow windows boot up ...) Anyway, I now I realize I don't know anything about laptop hard ...
18
votes
4answers
81k views

Is it possible to mount/unmount a physical hard drive in Windows XP?

Is it possible to mount/unmount a physical hard drive in Windows XP? Ideally, I'd like to be able to do this from the command line so that I could have batch files to do it, ie: mount.cmd unmount.cmd ...
18
votes
3answers
9k 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 ...
18
votes
2answers
448 views

An unknown tool is wiping our Virtual Machines and we can't ID it

A console view of a Windows 2008 R2 VM, on vSphere is showing the following screen: "Operation 2 of 2" "Wiping disk" Can someone advise on what this program is? Some information on this mystery: ...
17
votes
1answer
2k views

Why does unpartitioned Hitachi HDS5C3020 drive start consuming 50% more power 15 minutes after boot?

In a Debian 6.0.6 system there are 74 pieces of 2TB Toshiba DT01ABA200 drives. These drives are identified as Hitachi HDS5C3020BLE630 drives running firmware revision MZ4OAAB0. 64 Drives attached via ...
17
votes
4answers
1k views

Should you still spread a hard drive order over several vendors?

Once upon a time, I was taught that whenever I needed around six or more hard drives I should spread the order among at least two vendors, and three when the order gets up around 20 drives or more. ...