Hot answers tagged

175

This is going to be a function of your workload and the class of drive you purchase... In my server deployments, I have not had a properly-spec'd SSD fail. That's across many different types of drives, applications and workloads. Remember, not all SSDs are the same!! So what does "properly-spec'd" mean? If your question is about SSD use in enterprise ...


59

Every laptop at my work has either a SSDs or Hybrid since 2009. My SSD experience in summary: What I'll call "1st Generation" drives, sold around 2009 mostly: In the first year about 1/4 died, almost all from Syndrome of Sudden Death (SSD - It's funny, laugh). This was very noticeable to end users, and annoying, but the drastic speed difference made this ...


46

In the SATA specification this is referred to as hot plug and hot removal and they are two separate events. While the electrical and communication layers support both hot plug and hot removal, check that your drive controller, operating system, and drivers support them. Note that all of the below ONLY applies to host and devices (ie, drive controllers and ...


39

A few items to help clarify SAS technology... SATA drives can connect to SAS ports. SAS drives cannot connect to SATA ports. Server-class hardware typically uses an embedded RAID controller or a separate RAID controller PCIe device. Most RAID controllers and SAS HBAs will use SAS connections (multilane or 4-lane SAS ports). Internally, these systems will ...


19

Taken from there SFF-8087 Internal four channel connector (data only) The SFF-8087 connector is a very widely used connector type that is commonly used today on SAS cards. It carries the equivalent of four SATA/ SAS 7-pin connections through a SFF-8087 to SFF-8087 cable providing 12gbps of throughput using SAS or SATA II 3.0gbps devices. ...


18

In my experience, the real problem are the dying controllers, not the flash memory itself. I've installed around 10 Samsung SSDs (830, 840 [not pro]) and none of them has made any problems so far. The total opposite are drives with Sandforce controllers, i had several problems with OCZ agility drives, especially freezes in irregular time intervals, where the ...


18

The idea with ZFS is to let it known as much as possible how the disks are behaving. Then, from worst to better: Hardware raid (ZFS has absolutely no clue about the real hardware), JBOD mode (The issue being more about any potential expander: less bandwidth), HBA mode being the ideal (ZFS knows everything about the disks) As ZFS is quite paranoid about ...


15

When a drive has failed in some circumstances Linux won't realise you've actually pulled it physically from the array. If you have that problem (as I did this morning) you can do the following: echo 1 > /sys/block/<devnode>/device/delete e.g., in my case, /dev/sda had failed and I didn't want to reboot the server, so I did: echo 1 > /sys/block/...


15

It's a case of math. I/O-per-second is determined by the following calculation: Random I/O = 1000/ (average latency + seek time) For a 7.2K RPM drive, a seek-time of 8.5ms and latency of 4.16 gives an IOPS number of 78. For a 15K RPM drive, a seek-time of 2.6ms and latency of 2.0ms gives an IOPS number of 217 . For a 15K RPM drive, a seek-time of 3.4ms ...


15

Q. If one happens to have some server-grade hardware at ones disposal, is it ever advisable to run ZFS on top of a hardware-based RAID1 or some such? A. It is strongly preferable to run ZFS straight to disk, and not make use of any form of RAID in between. Whether or not a system that effectively requires you make use of the RAID card precludes the use of ...


13

As ewwhite points out they'll physically fit into the servers with the correct disk caddies but you don't have to look far online to read the tales of woe that people run into when using non-HP disks with HP controllers as HP-branded disks have specific firmware on them that extend the functionality, reliability and in some cases performance of their disks. ...


13

I was able to get this to work on my Western Digital WD20EURS. After piecing together tips from all over google, I was able to get a master password, research the commands of hdparm, and use your example in your original question to resolve my issue. Maybe this will help with you too. First off, I found a list of master passwords for various brands of ...


13

SATA/SAS are not like hubs, rather they work much like a network switch. This means that a single SATA/SAS port provides the entire advertised bandwidth, independently from the other ports. In other words, a chipset providing 4x SATA 3.0 ports (6 Gb/s each) has a "SATA backplane" switching capability of 4x6 Gb/s = 24 Gb/s. For a 4x SAS 3.0 ports (12 Gb/s ...


11

www.hardware.fr one of the biggest French hardware news site is partner with www.ldlc.com one of the biggest French online reseller. They have access to their return stats and have been publishing failure rate reports (mother boards, power supplies, RAM, graphics cards, HDD, SSD, ...) twice a year since 2009. These are "early death" stats, 6 months to 1 ...


11

Normally nothing has changed between the cables between SATA I,II and III. From the official SATA-IO document: The same cables and connectors used for current SATA implementations can be used to connect SATA 6Gb/s devices. SATA-IO recommends utilizing quality components to ensure data integrity and robust operation at the fast 6Gb/s transfer rate. ...


11

Yes, the extensive command set of the SCSI is a big bonus of using it over SATA. from SAS' Wiki: SATA uses a command set that is based on the parallel ATA command set and then extended beyond that set to include features like native command queuing, hot-plugging, and TRIM. SAS uses the SCSI command set, which includes a wider range of features like error ...


11

On Dell's R210, R220 and T130 I've successfully used Sandisk's consumer grade SSDs for years. I've done this with PERC's H410 and H710 controllers. It will be a matter of controller and controller's firmware more than server brand/model. Also, you'll probably have issues to find disk trays. I ended up buying it used on a famous refurbished hardware shop. ...


10

You can use either. Much of what's displayed depends on your controller and disks. I use SAS controllers and SAS disks (with SATA SSDs, in some cases), but you're free to use whatever you wish for your zpool drive identification. The reason you see ata and SCSI is the SCSI emulation layer in Linux here. Just make sure you DON'T use basic /dev entries like /...


10

You need a SAS expander and/or a server with a disk backplane that has an embedded expander... Please see: RAID card w/1x mini-SAS connector : how do I physically connect 16 disks? and How exactly does a SAS SFF-8087 breakout cable work? + RAID/connection questions


9

Yes, you can. (It's tacky, but it will work) Here's a very good reason not to... But if you choose to move forward... You'll need to place the drive in an HP drive carrier/caddy/tray. This is what secures the disk in the hard drive bay and provides hotplug connections to power and the SATA/SAS connection. This interfaces with the SAS SFF-8482 connector ...


9

I run ZFS on top of HP ProLiant Smart Array RAID configurations fairly often. Why? Because I like ZFS for data partitions, not boot partitions. Because Linux and ZFS boot probably isn't foolproof enough for me right now. Because HP RAID controllers don't allow RAW device passthrough. Configuring multiple RAID 0 volumes is not the same as RAW disks. ...


9

SCU means Storage Control Unit SCUs support SAS drives with HDD enable module installed SCUs do not support Optical Drives There is no practical performance advantage when using SCU Intel PCH supports two types of RAID controllers: AHCI and SCU The thing listed as PCH is the normal AHCI mode. The AHCI controller supports SATA drives and the SCU controller ...


9

Yes, you can swap HDDs <-> SSDs the way you want. Moreover, it's OK to use non-Dell branded SSDs inside Dell servers, you won't receive support (of course!) and some functions won't work like LEDs, iDRAC etc, but in general it's a way to go.


8

You're not supposed to do this. The HP Smart Array P410i RAID controller is not compatible with every SSD. You can't just toss some consumer drives into the server and expect them to work. HP protects/guards against that by restricting third-party drive use in their servers. The drives have NOT failed, but they definitely are not meant to be used with that ...


8

It's what happens when you let marketing people touch technical documentation. This particular server motherboard has a secondary SATA controller, to which the ports labeled SSATA1-4 are connected. It can be enabled or disabled independently of the other SATA controller in the system BIOS.


8

In most scenarios, including common virtualization workloads, the SSDs will outperform the HDD drives due to lower latency and higher IOPS. The link speed is a lot less relevant than latency or IOPS in most real world workloads, so I guess the difference is not too big. If you want actual numbers, you'll have to perform a benchmark with your workloads as ...


8

Yes, that is correct. There are multiple reasons for this: SAS drives are sold less, leading to scale effects. They are actually more reliable These 1.2 GB 2.5" are 10k RPM drives, so they are faster They have specific vendor firmware with proprietary features. You pay a premium for that alone. Also, depending on the vendor, you must use their ...


7

I can't believe nobody mentioned AHCI yet... your SATA controller has to be in AHCI mode to enable hot swap. Check this by looking at the driver you are using: root@peter:~ # find /sys -name sdk /sys/devices/pci0000:00/0000:00:11.0/ata5/host4/target4:0:0/4:0:0:0/block /sdk /sys/block/sdk /sys/class/block/sdk root@peter:~ # readlink /sys/devices/pci0000:...


7

It's a hard disk with a FC interface. Nope, you probably can't just arbitrarily replace one of them with a disk with a different interface, and different IO characteristics, especially in a storage array. But ask your vendor to be certain, or consult their documentation!


7

If you use the built-in SATA ports, you'll be limited to 2TB by the Intel 5000X chipset. You could put a SATA or SAS PCIe card in the server that supports larger drives.


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