Hot answers tagged

56

Check for files on located under mount points. Frequently if you mount a directory (say a sambafs) onto a filesystem that already had a file or directories under it, you lose the ability to see those files, but they're still consuming space on the underlying disk. I've had file copies while in single user mode dump files into directories that I couldn't ...


27

Just stumbled on this page when trying to track down an issue on a local server. In my case the df -h and du -sh mismatched by about 50% of the hard disk size. This was caused by apache (httpd) keeping large log files in memory which had been deleted from disk. This was tracked down by running lsof | grep "/var" | grep deleted where /var was the partition ...


16

See what df -i says. It could be that you are out of inodes, which might happen if there are a large number of small files in that filesystem, which uses up all the available inodes without consuming all the available space.


16

This has been covered here... See the related links on the right pane of this question. Right now, the market conditions are such that you should try to use SAS disks everywhere you can. Enterprise SAS disks are your fastest and most resilient rotating media available at 10,000 and 15,000 RPM. Performance-optimized Nearline or Midline SAS are usually ...


15

The conversion of a SCSI chassis DL380 G4 to the SAS chassis is possible, but not at all practical. It requires a bezel change, backplane modification, a new drive cage, a Smart Array P600 RAID controller (or SAS/SATA HBA) and will be severely crippled in performance. In addition, it can only accommodate 2.5" small-form-factor 1st generation SAS and SATA ...


12

2.5" hard drives have a much smaller platter diameter and thus there is a smaller mass that must be moved while friction is reduced as well. On the other hand, the operating range of the slider (which carries the heads) is smaller, which has a positive impact on access time if you compare 3.5" and 2.5" at equal rotation speeds and mechanical components. A 2....


11

I agree with OldTroll's answer as the most probable cause for your "missing" space. On Linux you can easily remount the whole root partition (or any other partition for that matter) to another place in you filesystem say /mnt for example, just issue a mount -o bind / /mnt then you can do a du -h /mnt and see what uses up your space. Ps: sorry for ...


11

Old NeXT hardware. SWOON! Getting a SCSI2 -> SCSI 1 adapter should be trivial. There were both internal and external varieties. Google is your friend. For some reason I thought the "newer" slabs should be SCSI2 but it's been a long time. You still have to terminate the SCSI chain. Keep to addresses 0-7. Further just Googling for "scsi-2 pci card" comes up ...


11

The three values stand for channel, SCSI target ID, and LUN. The dashes act as wildcards meaning "rescan everything" A quick google search turns up this RHEL doc (and dozens of other answers) This is the same command described in Section 7, “Adding a Storage Device or Path” to add a storage device or path. In this case, however, the channel number, SCSI ...


9

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/...


9

SAS is largely an "enterprise" tech whereas USB is most definitely not (at least as far as storage goes, anyway). I'm guessing this is why you haven't found any suitable adapters. That said, you're going about this the wrong way. With a good backup regimen, you dont need the original hardware. So, get a good backup system in place and this issue is ...


9

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 /...


8

The Zeus IOPS SSD (used by Oracle storage and others) uses SAS interfaces at 3G or 6G. http://www.stec-inc.com/product/zeusiops.php In addition, the Sandisk/Pliant line has SAS 6G interfaces. http://www.sandisk.com/business/industries/enterprise/ Other options are listed here: http://www.storagesearch.com/ssd-sas.html


8

The other guys have answered very well but I have a pet-subject that I like to roll out whenever this kind of thing raises its head - what's known as 'Duty Cycle'. 'Duty Cycle' is the workload that the disk manufacturer anticipates the disk will use and it designed to work most reliably at. For instance many 'enterprise' disks have a 100% 'duty cycle' - ...


7

"Near-line" is a marketing term for "7.2K RPM drives not designed for 24/7/365 continual usage". Using them in such a role will result in an increased failure rate compared to drives designed to be used flat out for years at a time. SAS vs SATA, in many cases there are little meaningful differences between the two bus specs, but SAS was designed for ...


7

I've built many of these systems... Your issue is an easy fix. This is an old server, so I wouldn't invest much time, however the HP ProLiant DL380 G4 was an odd unit. I presume you have a SCSI model with 6 U320 SCSI drive bays in the front. In order to resolve your situation, you should understand that the server has an onboard Smart Array 6i RAID ...


7

In the Red Hat storage administration guide, the method you mentioned is there, along with some other options which you might prefer. echo "- - -" > /sys/class/scsi_host/hosth/scan [...] This procedure will add LUNs, but not remove them. There's also the less arcane /usr/bin/rescan-scsi-bus.sh, which has the advantage that it can also remove ...


7

Oh my... What are you trying to do?!? This is a definitely a square-peg in a round-hole issue. SCSI is not SATA or SAS. Your Dell server is a PowerEdge 1850, which featured parallel SCSI (Ultra-320 SCSI) drives. These disks connected to an 80-pin SCA connector on the drive cage backplane. SATA and Serial-Attached-SCSI (SAS) superseded the old Parallel ...


6

To add a little bit to Stephen Thompson's answer which was good. Currently the largest SAS 2.5" drives are 146 GB for 15k, and 300 GB for 10k. One reason why the SAS 3.5" disks have relatively poor density, is that the platters themselves are far from filling the case, closer to 2.5" size actually. This is AFAIK due to problems with larger platters ...


6

For the sake of simplicity when I say "SCSI" I'm talking about "traditional" SCSI and SAS So, on the most basic level SCSI drives will be more reliable simple because they are built better. They are designed and priced to be put into high end machines - primarily servers where they will get a lot of abuse and quite possibly run 24/7/365 for 5-7 years. They ...


6

The Atlas series was a noisy drive. There are two possible reasons for clicking with them. They have a notoriously noisy park mechanism which is probably what you've been hearing for all this time. The second thing that the Atlas series did was click when the drive hit either extreme point of extension. The Seagates to my knowledge didn't have the same ...


6

Yes. It's like SATA in that the connectors are compatible in both directions, minus the speed improvements of course. (This is true at least for the SFF-8482/SFF-8484 connectors).


6

Your SAS to SATA adapter isn't a protocol translator, just a pin to pin adapter. It won't let the USB to SATA adapter speak to the SAS drive in any language other than SATA... which it won't support. So you won't see anything happen.


6

Shoe-shining refers to the tape drive stopping and rewinding due to an empty data buffer or inconsistent incoming data stream. This was a problem with older DLT drives. LTO drives shouldn't experience shoeshining. The LTO format/standard was partially designed to eliminate this behavior. HP drives, in particular, have a variable write speed to help reduce ...


6

Realistically speaking, you're doing your employer a disservice trying to drag a machine with such old technology into the future. It's time to buy a new machine. By the time you spend the time cobbling together this bespoke solution you'll have spent more of their money than just buying a new machine. You're also leaving a major headache for the next person ...


5

Avoid SATA tape drives - the only one's I know of take DAT/DDS tapes (which is a horrible format). I'd suggest a SAS or SCSI LTO3/LTO4 drive. LTO is effectively the standard tape format.


5

You've got a pretty small sample size. I wouldn't think anything of it. Unless there's some statistically significant evidence available from somewhere, I don't think it's possible to draw a conclusion one way or another.


5

I buy my HP disks from HP, my NetApp disks from NetApp, my EMC disks from...etcetera etcetera - that way I know they're fully supported and I won't be left 'holding the baby' if things start going wrong.



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