Hot answers tagged

23 votes

Linux goes to swap while plenty of RAM installed

There is no problem. Even if there is still available RAM, the Linux Kernel will move memory pages which are hardly ever used into swap space. It’s good to swap out memory pages that have been ...
  • 2,980
21 votes

Why should iscsi traffic be isolated?

Because: Very, very bad things will happen if someone gains unauthorized access to your storage network Very, very bad things will happen if you have your iSCSI traffic not separated, and someone ...
  • 19.6k
20 votes
Accepted

Poor iSCSI performance with SSD disks and 10 Gbe network

Short answer: This is the results of network latency and a serial workload (as you imposed by using direct=1, sync=1 and iodepth=1). Long answer: using direct=1, sync=1 and iodepth=1 you created a ...
  • 44.4k
17 votes
Accepted

Shared access to iSCSI target

To have multiple initiators share a single target, whether over ISCSI, Fibre Channel or other SAN solution, you need a cluster-aware filesystem. VMWare ESXi does this with VMFS. Veritas offers one in ...
  • 1,708
15 votes
Accepted

iSCSI, multiple initiators for the same LUN

You need to have some sort of either a clustered file system or distributed lock manager to avoid metadata damage done to your file system with concurrent writes. There's a good summary of this ...
11 votes

Low performance both iSCSI and AoE

To squeeze maximum performance out of iSCSI connected storage you should use Jumbo Frames and MPIO (not LACP). RDMA/iSER is recommended if you can do that. AOE (ATA over Ethernet) is old and is shit....
  • 5,626
8 votes
Accepted

Is SMB safer than iSCSI for connection to a NAS?

Any online writable disk can be corrupted by a malicious software or user. Underestimating them by assuming they cannot find a file share is a mistake. Last line of defense for important data is ...
7 votes
Accepted

Complete High Availability System

If you do have just one Synology box shared between your Hyper-V machines, it can still be considered as a SPoF. It dies, you lose all the LUNs sitting there. For true HA you would need a second NAS ...
  • 8,808
7 votes

How to specify sector size for LVM logical volume?

The fileio backing store driver is the way you would accomplish this. Consistency is only a concern if you choose to enable writeback caching (or as targetcli refers to it, "buffered mode") on the ...
  • 7,006
7 votes

Microsoft iSCSI target server 2016 failover cluster doesn't work in Server Manager after transfering roles

I see similar issue posted on technet. Is there any chance to see what does Event Log show? For the case, from my experience, Microsoft iSCSI target is too slow. Currently, I use StarWind Virtual SAN ...
7 votes

Can I mount a block device both over iSCSI and locally?

Using one drive for multiple connections without clustered file system is a suicide. Data corruption is the first that you will see after a few data iterations. You must run clustered file system to ...
  • 5,196
7 votes

How to configure StarWind Virtual SAN Free

First off, get rid of NIC teams for your storage and synchronization networks. ISCSI networks leverage MPIO, there is no need for trunking, teaming, bonding, etc. Also, don't forget to enable MPIO in ...
  • 5,626
7 votes
Accepted

PAGE_FAULT_IN_NONPAGED_AREA when booting Windows 10 from iSCSI network drive

This appears to happen when the system page file is located on the iSCSI device. While locating the page file on iSCSI worked fine under Windows 7, it appears to be broken in Windows 10. Unfortunately,...
7 votes

Slow sequential speeds on 9x7-drive raidz2 (ZFS ZoL 0.8.1)

Good question. I think your sparse zvol block size should be 128k. Your ZIO scheduler settings should all be higher, like minimum 10 and max 64. zfs_txg_timeout should be much longer. I do 15 or 30s ...
  • 195k
7 votes

ISCSI and Windows Server 2019

iSCSI as a protocol is not limiting performance or latency on spindle (HDD) drives. It may limit on SSD and will limit on NVMe. The performance in this case depends on: 1) Physical storage. You can ...
  • 8,808
7 votes
Accepted

"Bad message" with a new SAN using multipath and iSCSI

That is normal behavior for a non-clustered file system. To use iSCSI SAN with Ubuntu compute servers, a clustered file system should be used. You should probably learn more about GPFS, GFS2, Lustre, ...
  • 1,476
7 votes

Is SMB safer than iSCSI for connection to a NAS?

Leaving the question of iSCSI vulnerability when using it without a clustered file system but with multiple initiators aside, I can hardly find any clear reason why file sharing protocol would be more ...
  • 8,808
6 votes

Why should iscsi traffic be isolated?

Because not doing so allows regular traffic to impact on storage traffic, which is a bad idea as it means that say a user's download could delay an important read or write.
  • 100k
6 votes
Accepted

Is there any downtime when expanding a volume on an iSCSI setup using Synology Hybrid RAID?

No there wont be any down time, this really is a standard thing to do now in enterprise, where always up availability is key. LVM does this expansion in the background and it is pretty much instant,...
  • 540
6 votes
Accepted

How to know when to properly use iSCSI, NFS or SMB?

I am presented with SMB, NFS and iSCSI options to connect to the server. Meaning, I have the option of either setting up a share via NFS or SMB or creating a virtual iSCSI drive in which I can ...
  • 3,522
6 votes
Accepted

What is better: iSCSI or NFS for mysql datadir mount?

Network filesystems and databases can be a problematic combo, and at least InnoDB does not like NFS. From the MySQL documentation If reliability is a consideration for your data, do not configure ...
6 votes
Accepted

Fiber Channel (8 Gb) or iSCSI 10 Gb

iSCSI will be fine here, especially since you already have so much of the infrastructure for it. While fiber would be less susceptible to interference, a 2Gb/s difference is enough to make up for that ...
  • 7,006
6 votes

Low performance both iSCSI and AoE

Your expectation on how Ethernet link aggregation works are incorrect. All aggregation methods other than balance-rr (ie: all methods whose mode > 0) do not give you a greater single-connection ...
  • 44.4k
6 votes
Accepted

How can I convert a iSCSI system disk from XenServer to another format

To get disk image do P2V and/or V2V: attach iSCSI to Windows by ISCSI initialtor. create VHDX using Disk2vhd (https://technet.microsoft.com/en-us/sysinternals/ee656415.aspx) convert VHDX to QCOW ...
6 votes
Accepted

How to connect two Dell storage arrays to a to a Dell Poweredge server (daisy chain vs direct)?

You can stack the MD unit that way; (In the image its 3 MD, but you can see how) For your openmanage question, yes, it can be used remotly, but be sure to set the routing correctly in the management ...
  • 16.4k
6 votes
Accepted

only one of two SFP ports reachable on iSCSI SAN

Never use LACP or any other kind of network aggregation for iSCSI networks unless it was required by your SAN vendor. Use MPIO (Multipathing) instead.  Generally speaking, teaming creates a network ...
  • 5,626
6 votes
Accepted

How can I determine if an iscsi device is a mounted Linux filesystem?

Try iscsiadm -m session -P 3 and check the last section "Attached SCSI devices" Just FYI: If you set iscsid to start on boot you do not need to unmount/logout iSCSI partitions prior to reboot. As ...
  • 571
6 votes

Windows 10 iSCSI Boot

I can suggest you two options. First option is to use Linux gPXE. It is PXE client implementation and bootloader derived from Ethernet. I’ve heard about this solution a couple of times already, but ...
  • 5,196
6 votes
Accepted

Can I mount a block device both over iSCSI and locally?

Short answer: Don't do that Long answer: to double-mount a block device on two different machines, you need to use a cluster filesystem, as OCFS or GFS2. On the other hand, EXT4 is not a clustered ...
  • 44.4k
6 votes

Windows 2012 R2 Hyper-V SAN Configuration

Unless you're planning to do sort of a failover cluster with a pass-thru disks (and you're unlikely...) you need to wrap a Cluster Shared Volume (CSV) on top of your shared LUN. Use Cluster Shared ...

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