Questions tagged [hard-drive]

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

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183
votes
2answers
42k 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?
129
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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?...
106
votes
9answers
177k 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) ...
105
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8answers
20k 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 our ...
96
votes
10answers
10k views

Is it better practice to buy RAID disks individually vs. in bulk?

This may sound like an odd question, but it's generated some spirited discussion with some of my colleagues. Consider a moderately sized RAID array consisting of something like eight or twelve disks. ...
94
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17answers
52k views

Does drilling a hole into a hard drive suffice to make its data unrecoverable?

We have a lot of PCs in the company and nobody wants to wipe a multitude of hard drives. We also have many apprentice toolmakers who really want to destroy things. Thus, every couple of months, our ...
72
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17answers
16k 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.
69
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13answers
20k views

SSD or HDD for server

Issue I have read many discussions about storage, and whether SSDs or classic HDDs are better. I am quite confused. HDDs are still quite preferred, but why? Which is better for active storage? For ...
62
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8answers
6k 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 ...
50
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7answers
19k 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 ...
49
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23answers
11k 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 ...
47
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3answers
58k 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 ...
47
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10answers
15k 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 ...
47
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3answers
52k 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?
44
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11answers
24k 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 ...
42
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10answers
24k 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 ...
42
votes
6answers
6k 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-...
41
votes
7answers
111k views

dd on entire disk, but do not want empty portion

I have a disk, say /dev/sda. Here is fdisk -l: Disk /dev/sda: 64.0 GB, 64023257088 bytes 255 heads, 63 sectors/track, 7783 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (...
37
votes
9answers
53k 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 ...
36
votes
2answers
4k 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
14k 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 ...
32
votes
8answers
28k 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....
32
votes
9answers
23k 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 ...
31
votes
9answers
16k 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&...
30
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11answers
58k 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 drive....
30
votes
2answers
15k 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 Enterprise Storage so expensive?. My question is specifically about SAS drive enclosures, and justifying their expense. ...
29
votes
7answers
88k 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 ...
28
votes
8answers
10k 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 ...
28
votes
2answers
12k 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 ...
28
votes
3answers
108k views

How can i check remaining disk quota?

df does only report the disk free space, how can i get my allowed free space ?
27
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14answers
48k 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-...
27
votes
6answers
19k 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) ...
27
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4answers
28k views

Limit Linux background flush (dirty pages)

Background flushing on 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/...
25
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 ...
25
votes
4answers
49k 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. ...
25
votes
2answers
40k views

High disk I/O - jbd2/sda2-8 process

I have run a file server on a CentOS 5.8 final server. My only concern at the moment is what appears to be intermittent but continuous high disk I/O activity causing a general slowdown because of ...
24
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 ...
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
6k 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 ...
24
votes
13answers
3k 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 ...
24
votes
4answers
10k 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
8answers
629k 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 32&...
23
votes
5answers
5k 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 ...
23
votes
6answers
14k 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 ...
23
votes
3answers
28k 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 ...
22
votes
6answers
25k views

How do I easily repair a single unreadable block on a Linux disk?

My Linux system has started throwing SMART errors in the syslog. I tracked it down and believe the problem is a single block on the disk. How do I go about easily getting the disk to reallocate that ...
22
votes
9answers
81k views

How much space should you leave free on a hard disk? [closed]

Is there a rule of thumb for how much space to leave free on a hard disk? I used to hear you should leave at least 5% free to avoid fragmentation. [I know the answer depends on usage (eg: video files ...
22
votes
3answers
3k 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 ...
22
votes
4answers
61k views

Would SSD drives benefit from a non-default allocation unit size?

The default allocation unit size recommended when formatting a drive in our current set-up is 4096 bytes. I understand the basics of the pros and cons of larger and smaller sizes (performance boost vs....
22
votes
1answer
319 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 ...

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