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

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140
votes
2answers
27k 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? ...
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 ...
3
votes
3answers
5k views

What are the differences between consumer grade SSDs and the much more expensive enterprise SSDs?

I am in need of a terabyte or so of storage space for Lucene indices on a testing server. I'm having a hard time differentiating between disks like the Samsung 840 evo for about $450 vs SSDs with ...
44
votes
3answers
49k 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?
29
votes
2answers
11k 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. ...
9
votes
4answers
2k views

root full Linux. No free blocks

df -h reports the '/' partition to be 100% full. While running du -hs * on each directory of this partition shows there is still lot of space. tune2efs which reports just one block to be free. Ran ...
21
votes
3answers
50k 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 ...
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 ...
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 ...
15
votes
8answers
9k 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 ...
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 ...
8
votes
5answers
10k 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 ...
7
votes
3answers
27k views

How do you passthrough native SATA drives to a guest on ESXi?

I have ESXi 4.0 running on an Intel DX58S0 Mothboardboard with an Intel Core i7 930 processor. VT-d is also enabled. I have three drives in the system, drive 0 is used for ESXi. Drive 1 and 2 ...
6
votes
1answer
2k views

No space left on device — but there is space

I'm running an Ubuntu 12.04.1 server in a VMware virtualized environment that has a strange issue. Twice now, at seemingly random times, the machine has suddenly been unable to write to the root ...
4
votes
2answers
270 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. ...
3
votes
2answers
2k views

Move /var to new set of disks

I currently only have remote access to this CentOS box, I need to move /var form the primary RAID to a new set of disks that was installed with more space, My current thoughts on how to accomplish ...
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 ...
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 ...
19
votes
7answers
22k 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 ...
23
votes
14answers
33k 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 ...
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 ...
14
votes
9answers
18k 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 ...
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 ...
14
votes
6answers
9k views

SATA Disks that handle write caching properly?

It's pretty common to see advice to disable the write cache on individual disks used for databases because otherwise some disks will acknowledge writes that haven't yet made it to the disk surface. ...
5
votes
2answers
11k 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 ...
19
votes
6answers
7k 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 ...
5
votes
2answers
6k 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 ...
-1
votes
3answers
1k views

Looking for Hard Drive Health Monitoring software [closed]

I am aware that the current standard method of drive redundancy and backups would be a better solution, but I would be interested if there was a software that could be installed on workstation ...
56
votes
8answers
86k 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) ...
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 ...
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 ...
16
votes
2answers
20k 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 ...
13
votes
6answers
18k 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 ...
36
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 ...
15
votes
8answers
37k 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 ...
15
votes
6answers
26k views

Linux - Help, I'm running out of inodes!

I have a filesystem that has lots of small files. Currently about 80% of inodes are used (I checked with df -i), however only 60% of disk space is used. How can I 'increase' the number of inodes? If ...
12
votes
3answers
12k views

Linux disk IO load breakdown, by filesystem path and/or process?

Does anyone have experience with a tool that can provide an indication of disk IO load by filesystem path. I use to 'iostat' utility, frequently, to learn how much disk activity is taking place on a ...
6
votes
3answers
3k views

Linux different size for df and du for root partition

On my CentOS server, both of the commands are showing different usage for disk / , df shows this output: Filesystem Size Used Avail Use% Mounted on /dev/xvda2 16G 14G 952M ...
5
votes
12answers
27k 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 ...
9
votes
5answers
88k 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 ...
5
votes
1answer
2k views

iotop and iostat disagree

I'm trying to understand what's going on with my server's disks. It's running Ubuntu 12.04LTS and I'm used to using iostat to know when the disk is the bottleneck. But iostat -xd looks to me like ...
2
votes
1answer
2k views

Identify disks in vCenter to partitions in Linux guest

What I am trying to accomplish is to correlate hard drive in vCenter to the disks in the Linux guest. So here it goes Opening up settings for the guest in vCenter and moving to hardware tab, shows ...
10
votes
3answers
36k 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 ...
3
votes
2answers
463 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
1k 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
173 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 ...
1
vote
1answer
2k views

How to determine a disk consuming service in Windows 2008 server?

How to determine a disk consuming service in Windows 2008 server? I have a problem on Windows 2008 server with a constant growing used disk space? How to determine which service consuming most of the ...
4
votes
1answer
515 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, ...
4
votes
4answers
1k views

Disk full on linux server, blocks used is much less then blocks avalable

Output of df is: [root@backup log]# df Filesystem 1K-blocks Used Available Use% Mounted on /dev/mapper/VolGro 1889811408 1861658948 0 100% / /dev/sda1 101086 ...
3
votes
4answers
22k views

How long does it take to fsck a volume?

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