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

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111
votes
2answers
17k 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? ...
71
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 ...
42
votes
3answers
48k 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?
19
votes
3answers
29k 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 ...
40
votes
23answers
7k 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 ...
29
votes
2answers
7k 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. ...
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 ...
15
votes
8answers
6k 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 ...
14
votes
2answers
6k 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 ...
7
votes
3answers
22k 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
5answers
8k 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 ...
9
votes
4answers
1k 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 ...
4
votes
2answers
252 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. ...
29
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 ...
23
votes
14answers
23k 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 ...
20
votes
4answers
2k 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 ...
11
votes
9answers
10k 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 ...
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 ...
5
votes
2answers
4k 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 ...
13
votes
6answers
8k 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. ...
6
votes
1answer
1k 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 ...
41
votes
8answers
54k 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) ...
18
votes
3answers
14k 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 ...
116
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 ...
14
votes
2answers
12k 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 ...
10
votes
5answers
14k 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 ...
9
votes
7answers
12k 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 ...
32
votes
11answers
11k 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 ...
11
votes
8answers
23k 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
6answers
18k 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 ...
9
votes
3answers
11k 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 ...
9
votes
5answers
81k 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
3answers
1k 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 ...
4
votes
12answers
18k 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
3answers
30k 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 ...
5
votes
1answer
816 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 ...
4
votes
1answer
368 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
233 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
971 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
499 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 ...
1
vote
1answer
132 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
1k 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
4answers
738 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 ...
2
votes
0answers
356 views

What might cause DIR $file to report “File not found” when DIR $dir shows the same file just fine?

I can DIR a file and it doesn't exist, but DIRing its directory, or a file in the same directory as it, works fine. Is this a hardware or software problem? If it's hardware, is it the drive or ...
2
votes
1answer
319 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 ...
2
votes
2answers
343 views

Detecting Disk Writes Linux

my webserver running centos 5.7 is showing quite a lot of disk write activity which I cannot explain really. I run a few websites on this server with the help of nginx and php-fpm and xcache. On the ...
1
vote
3answers
13k 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 ...
1
vote
4answers
4k views

100% disk full on Centos?

Can someone tell me, why is this 100% used on the /? How can I fix this problem? I'm not a unix admin, I'm a programmer but can read the books. [root@datasrv /]# df Filesystem 1K-blocks ...
0
votes
2answers
284 views

Partition keeps filling up, don't know why

My partition /dev/sda1 keeps filling up. Besides the "/" directory, I cannot tell what directories are even on this partition in order to search for files to delete. I was able to get it down to 97% ...
0
votes
3answers
904 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 ...